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|x^2 - 12x| = 8 2004-01-24
From Sherre:
|x2 - 12x| = 8
Bundles of asphalt shingles 2004-01-24
From Larry:
According to my study material 4:12 multiplying factor for shingles is 1.054. The question reads as follows: A building with a floor plan of 3350 sq. ft. and a roof slope of 4:12 will require _______ bundles of standard asphalt shingles.
x^x^x^x^... 2004-01-23
From Ryan:
you have a number say x and it is to the power of x which is to the power of x and so on infinite times like x^x^x^x^x^x^x^... i have to figure out what x is so that the answer is always 2
A counterfeit coin 2004-01-23
From Kim:
You are considering buying 45 silver coins that look alike, but you have been told that one of the coins is a lightweight counterfeit. Find the least number of weighings on a balance scale that you can use to be certain you have found the counterfeit coin?
g on Mars 2004-01-22
From RC:
To measure the acceleration on Mars an object is dropped from a height of 160m. It takes 10s for this object to hit the ground. What is the value for g on Mars?g
A game with some strings 2004-01-22
From Trudy:
A boy holds 6 pieces of strings in his hands with the ends protruding above and below. The top ends are tied together in pairs and then the lower ends are tied together in pairs. What is the probabilty that the pieces of string are all joined in one loop?

What is the probability of obtaining two loops? Can you generalise this to solve the problem for 2n blades of grass?

Answered by Andrei Volodin and Penny Nom.
BEDMAS 2004-01-21
From Jessica and her mom:

my mom and I were wondering 2 things.

1. what is the reason for having bedmas.
2. 5+5-4+[6x3-(6+1-3x2) -5+9]

A problem with sets 2004-01-20
From Jason:

Given that the universal set S is the set of all sports fans, and

F={x|x is a football fan}
H={x|x is a hockey fan}
a)Describe (F^B)' (f intersect b)' in words
b)Draw a Venn Diagram and shade the region that represents the set of football fans or both basketball and hockey fans.

What is the speed of the automobile? 2004-01-20
From Rita:
An automobile travels toward Nashville from Cookeville. It takes 33 minutes to travel from Cookeville to Manchester, which is a 36 mile distance. If the driver continues at this pace, what is the speed of the automobile?
A parabolic arch 2004-01-19
From Teresa and Robyn:
A bridge over a river is supported by a parabolic arch...arch is 200 m wide at water level...the maximum height of the arch is 80 m..what is the height of the arch measured from a point on the water 40m from the centre of the arch
The product of any n consecutive integers 2004-01-18
From Fazia:
I have to prove that the product of any n consecutive integers is divisible by n!(eg:the product of five consecutive integers is divisible by 5!) It's easy enough to plug in numbers and prove it is true, but i'm finding it difficult to come up with a proper proof.
Combinations of 12 numbers 2004-01-18
From Cheryl:
I would like to know the total possible combinations using the numbers 1-12. We would also like to know the formula used to calculate the number of combinations.
Cubic yards in a concrete wall 2004-01-18
From Danny:
I am studing for my contractors exam. I am haveing truble with a few questions. I have the answer to the problems but I dont know how to get them my self.

How many cu. Yds. Of concrete are in a wall that is 150' long and 8'4" high an d 8' thick

Some trig problems 2004-01-18
From Weisu:

I have some questions about pre-calculus.

(1) (2(cos(x))^2)+3sin(x)-1=0
(2) sin(x)cos(x)=(1/2)
(3) 3sin(x)=1+cos(2x)
(4) tan(x)*csc(x)=csc(x)+1
(5) sin(arccsc(8/5))
(6) tan(arcsin(24/25))
(7) arccos(cos(11pi/6))
the last problem uses radian measure.

Two consecutive negative integers 2004-01-17
From Amanda:
Find two consecutive negative intergers whose product is 182.
Six letter words 2004-01-17
From Debora:
An anthropologist discovers an isolated tribe whose written alphabet contains only six letters (call the letters A, B, C, D, E, and F). The tribe has a taboo against using the same letter twice in the same word. It's never done. If each different sequence of letters constitutes a different work in the language, what is the maximum number of six- letter words that the language can employ?
Arrays of pennies 2004-01-17
From Kathleen:
How do I create an array of 100 pennies?
Volume of a tube 2004-01-14
From Mike:
where can you find how to get volume of a tube: 3 in across x 3 inch high
5 in across x 5 inch high
same formula for both. ONE will get the other.

3/8 as a decimal 2004-01-13
From A student:
My Math Midterm is tommorow and I am stumped... how do you turn 1 and 3/8 into a decimal... I know the answer is 1.375 but I just copied down what the teacher wrote on the board.
Oh, and what are the three cases of percents?

What is a Fact Family? 2004-01-13
From Keisha:
I am helping my child with his homework. The worksheet we are trying to do ask the child to choose a number from inside of a circle and then one from inside of a triangle and use the number to build a fact family. The title of the worksheet is "Building a Fact Family House". I noticed that Silver Burdett Ginn,Inc. was the publisher of the book the worksheet came from so I was on the website trying to find an answer to my question. My question is "What is a Fact Family?"
Polynomial division 2004-01-13
From Efrat:

How do we divide the following polynomials?

(x3 + x2 - x + 2) / (x + 2)

Twelve acres 2004-01-13
From Heather:
I am looking at buying a property that includes 12 Acres of land and I am trying to visualize what this size is equivalent to. I have searched your site and figured out how many square feet it is but I was hoping that you could apply 12 Acres to something tangible, like a football field!
Why is the letter J used for the integers? 2004-01-13
From Amanda:
Why is the letter J used to represent intergers as a symbol?
The square footage of an acre 2004-01-12
From Paul:
What is the square footage of an acre of land assuming all four sides are equal in length.
Permutations and combinations 2004-01-11
From A student:
Are there more permutations than combinations for a series of 4-digit numbers with the integers 0-9? Can you illustrate calculations?
Cubic furlongs 2004-01-11
From A student:
1 mile=8 furlongs, how many cubic furlongs in a cubic mile?
Reflex angles 2004-01-09
From Sonya:
My daughter is searching for examples of reflex angles. We already have the hands of a clock but still need another example. Can you help us.
Geoboards 2004-01-09
From Elissa:
What is a geoboard? I have a young girl in grade eight math who has a math question using a geoboard.
The area of a lot 2004-01-09
From Lea:

I have a problem. I am interested in purchasing a piece of property which has the following dimensions. It is 259.10 Feet on the north side x 61.20 Feet on the east side x 217.80 Feet on the south side x 196.70 Feet on the west side. It looks like an irregular rectangle shape. How do you figure out the square footage on this irregular sized property, and what is the correct square footage answer.

I have attached a survey map.

Inequalities 2004-01-08
From Michael:
How do you use inequalities in your job and in your everyday life?
Dividing zero by infinity 2004-01-08
From Jason:
What do you get when dividing zero by infinity? Our Calculus teacher was pretty sure that the expression was indeterminate from. However, if this is so...Why? Zero divded by any number (except zero) is zero, true. Any number (except infinite) over infinite is zero. So, why isn't Zero divided by infinite zero. A simpler way if I had 4 potatoes and was to split them among 2 friends, each friend would get 2 potatoes. However, if I had 0 potatoes and split them a infinite number of ways, each person would still have 0. Explain please!
Unusual occurances 2004-01-08
From Martin:
My wife and I have a question about the probability of something that happened to us a few years ago. So far, no one has been able to give me even an approximate answer. On my 32nd birthday, my wife and I went out to eat at local Japanese hibachi style restaurant. At the restaurant, couples/families are sat together around the hibachi where the cook performs a show. There was a fifteen minute or so wait, so my wife and I sat in the lounge waiting for our name to be called. When they called our names for the reservation, this is what happened. The first group called was the Martin family. Then they called the Francis family. We were the next family to be called, the Ashton family. My full name is Martin Francis Ashton! I think the odds of that happening to someone are very unlikely, but it did, and there is more. Next, we were all sat at the same table in that order, "Martin" family, "Francis" family, then us, the "Ashton" family. Again, it formed my full name!
Is zero even? 2004-01-07
From A secretary at an elementary school:
Is zero an even number?
The sides of a circle 2004-01-07
From Helena:
My name is Helena and I am 10 years old. On a resent math exam I was asked the question" How many sides does a circle have?" and I wrote down none. The teacher said the answer was one side.
Laying decorative bricks 2004-01-07
From Duk:
Loren is laying decorative brick along both edges of the 21-meter walkway up to his house. Each brick is 0.26 meters long. He is placing the bricks end to end. How many bricks does he need to do the job?
Factoring expressions 2004-01-03
From A student:

I'm having trouble factoring expressions that aren't monic. I can do things like x2-9x+8, but problems like 12x2+5x-3 have me stumped.

I also have a question about factoring out common factors. In a problem like x2-18x+81, wouldn't you divide by 9? But what happens to the x2, is it x2/9?

37 with four 4'2 2004-01-03
From Myra:
Using four fours and only four fours to get an answer of 37.
Solving an equation 2004-01-03
From A student:
the question is to solve and check equations and the question is
2n + 3n + 7 = -41

Making a windmill 2004-01-02
From Matthew:
I am a farmer in Ontario. It has been almost 20 years since high school. I am toying with making a windmill. The output chart for the the old generator I have is shown below. Before I tear it appart I would like to develop a formula from the chart that can predict the output at various speeds.
Four digit combinations 2003-12-31
From A student:
i need all 4 digit combinations using 0-9 please
Fractions 2003-12-31
From Jae:
Replace the question marks with numbers that will make the sentence true.
1.1/3=?/9=?/6
2.?/18=8/12=4/?
3. 3/?=12/?=9/?
4.?/3=?/21=?/7
5. Which problems have more than one possible answer? Why do you think this is so?

A new way to measure randomness 2003-12-31
From Stephanie:

Last year, I did a science project in which I asked, "Which shuffles better, an automatic card shuffler or shuffling by hand?" To measure this I decided the "best" shuffler was the one to become random first. Last year, to measure randomness, I numbered cards 1-52 and had the subjects shuffle them until they broke up the rising sequences or reached 10 shuffles. (Usually 10 shuffles came first...) Anyway, I did the same thing with the automatic card shuffler, and, as hypothesized, the automatic card shuffler randomized the deck first.

This year, I have decided to continue the project. The problem is, I need a new way to measure randomness without the use of fancy computers or something. I have searched the Internet, I have posted my query on websites based on math, and I have searched the local library.

I have found many useful things on the Internet, but none of them can tell me a new way to measure randomness. I cannot do a perfect shuffle, and I am not terribly gifted in the art of using computers. If you have any information (anything will help) or advice, I would be greatly obliged.

The trapezoidal rule 2003-12-31
From Prashanth:
I have a set of XY co-ordinates(say 49 points),I want to find the area enclosed by the curve joining them and the axes.I do not have an equation for the curve and I am not able to fit a curve given the points.I use the trapezoidal rule (Y1+Y2/2)*(X2-X1), Is it right? can I do this with any other method?
Ratios and proportions 2003-12-31
From Frank:
I would like to know how you use 'ratios and proportions' in everyday life.
Some number problems 2003-12-24
From Shruthi:
1. Write 31 using 3 five times
2. Write 100 using all the 10 digits just once
.
.
.

Percent increase 2003-12-24
From Frank:
How does one figure the percent of increase or decrease in the cost of an item?
Making a cone 2003-12-22
From Tracie:

I am working on a craft project at home and I have been given the following information:
16" tall and 13" diameter at base, with 1 and 1/2 " opening at top.

Is there a basic formula for creating a cone with this info?

Answered by Claude Tardif and Penny Nom.
400, 100 and 2500 2003-12-21
From A student:
A person likes 400 but dislikes 300
He also likes l00 but dislikes 99
He also likes 2500 but dislikes 2400

Which of the following does John like
900, 1000, 1100 or 2400

The angles in a regular polygon 2003-12-21
From Ernie:
If i have a measure of one interior angle of a polygon, how can i find the number of sides it has?
From Paula:

e.g 90% + 80% + 60% + 54% + 25% = ?

From Ameer:
A businnessman drives from Washington, D.C., to Boston, a distance of 442 miles, and then makes the return trip. On the way to Boston, he drives 65 miles per hour, taking an 1-hour rest stop during the drive. After finishing his business in Boston, he make the return trip driving at 60 miles per hour and takes a 45-minute rest stop halfway through the trip. Which leg of the journey, Washington, D.C. to Boston, or Boston to Washington, D.C., takes the longer time?
The area of a plot of land 2003-12-19
From David:
I have a plot of land that I cannot find the square footage of. Actually my home sits on a large lot. Local building codes require that a home is seated on no less than 7500 square feet of land and have no less than 50ft of road frontage (the rear of the lot has 65ft of frontage on another road). I need to know if I have enough square footage to build a second home on the rear lot. The lot has five sides. Only one angle is a 90 deg. angle. The others I cannot determine. Of the 4 remaining angles, all 4 angles are obtuse, or greater than 90 deg. The dementions are 89.19' x 130' x 118.52' x 65' x 170.94'. The two legs that make the 90 deg angle are 89.19' and 170.94'. The measurements fall in order using the 90 deg angle as the point of origin and proceeding clockwise, 89.19', 130', 118.52', 65', 170.94'. I have used all the skill I can muster, however, it has been a long time since school and regretably I cannot find an answer.
Multiplier and multiplicand 2003-12-17
From Karen:
The K-5 curriculum states that at a grade 5 level students should "understand and use the terms multiplier, multiplicand" The curriculum defines 'multiplicand' as " a number being multiplied by another number. A factor." There is no definition given for 'multiplier' Question: Define these words- are they just other words for 'factors'. If so, how important is it that students use these terms? It would seem like 'factors' would be the better choice of words to use. If multiplcand refers to eg. the first factor in the equation and the 'multiplier' the seond term, (if in fact it does)- is this not confusing for students when we teach them that multiplication is commutative?
Binomial distribution 2003-12-17
From Lesley:
my daughter is having difficulty with the following formula P(X=x) = ( n over x) px (1-p) n-x
The teacher has given them the formula but not taught them how to apply it or understand it.

The hour hand and the minute hand 2003-12-17
From Minnie:
When you are looking at the clock at 12:00 the hour hand and minute hand are exactly together. (one on top of the other). Between 1:00pm and 1:15pm there is another time when the hour and minute hands are exactly together again.
Factoring in 2003-12-16
From Priscilla:
How can you use solving by factoring in real life applications?
An elliptical race track 2003-12-16
From Judy:
the inner rail of a race track is a perfect ellipse. the track is a standard width all the way around. how can i prove that the outer rail is a ellipse?
How far can you see? 2003-12-15
From Judy:

How far apart, assuming no obstacles, can two people stand and still see each other?

i know this deals with the curvature of earth, but i can't figure out the formulas involved.

(2^ 20,966,011) - 1 2003-12-12
From Reid:
Can someone please explain, answer and/or solve this: (2^ 20,966,011) - 1

I don't know what it means, my boss sent it out, I'm assuming it is to be solved but don't know what it is, any prompt help would be appreciated, very much so, in fact, thanks,...........

Math jobs 2003-12-12
From Veronica:
Do you know a couple of jobs I can get when I am older in Math?
A snowball melts 2003-12-11
A spherical snowball has diameter 10cm and density 0.75g/cm3. It is placed in a cylindrical can with diameer 12cm. After the snow melts it turns to water with density 1.0g/cm3. What will be the depth of the water in the can (to 1 decimal place)?
Diamonds and Pearls 2003-12-11
From Lauren:
A crown holds a total of 3080 jewels.
It is made up of diamonds and pearls.
There are 10 times as many diamonds as there are pearls.
How many pearls are there?

1/0 = ?? 2003-12-09
From Lisa:
One of my students asked me a fractions question. She knows that 0/1 equals 0 but does 1/0 also equal 0?
Answered by Walter Whiteley and Penny Nom.
Non-euclidean geometry 2003-12-08
From Geoffrey:
How can you use non-euclidean geometry to navigate on a sphere? What geometers did work in this area?
Matrices 2003-12-05
From Julie:
I am doing a project and need to find some mathematiciens who had an influence in matrices. I can't seem to find any when I search online. Could you please help me with this?
Prescription drug coverage 2003-12-04
Last week congressional approval was given to legislation involving prescription drug coverage for seniors. One summary of the legislation explains that it is estimated that in 2006 a senior will pay a premium of \$35 per month, then pay their first \$250 in pharmacy bills. After the bills reach \$250, the coverage would pick up 75% of their bills that bring their total bills between the \$250 and \$2250 mark. After their bills reached a total of \$2250, the senior would be responsible for all bills bringing their total annual bills between \$2250 to \$5100. Then any bills after the \$5100 mark has been reached will be 95% covered by the insurance. Using this information, letís analyze the situation of a senior who accumulates \$6000 in pharmacy bills over one year and has the insurance coverage. Over the course of this year, how many dollars will the senior pay?
What percentage of 6 billion is 40 million? 2003-12-03
From GiGi:
What percentage of 6 billion is 40 million?
The median 2003-12-03
From Christiane:
how do you find the median of this group of numbers:63,75,29,37,49?
Non-Euclidean geometry 2003-12-03
From Geoffrey:
What are the applications of Non-Euclidean geometry (especially hyperbolic and spherical)?
Four digit combinations 2003-12-02
From Deen:

Question:
i have 3 numbers and i have to come up with all the possible 4-digit combinations with those 3 numbers. Is there a formula for it?

Example:
given numbers are 1-2-9 and you need to break a 4 digit code. what are the posiible combinations that u can come up using the 3 numbers?

A locus 2003-12-02
From Tash:

Question:

a)Find the equation of the locus of the point P which moves so that its distance from A(1,2) is always three times its distance from B(5,6)

b) Show that this locus is a circle and states the coordinates of its centre and the length of its radius

Finding angles 2003-12-02
From Jason:
I AM TRYING TO SOLVE A TRIG PROBLEM AND HAVE FORGOT HOW TO DO IT. WHAT I HAVE IS A RIGHT TRIANGLE WITH SIDE A BEING 14 FEET AND SIDE B BEING 3 FEET, USING PYTHAGOREAMS THEOREM SIDE C SHOULD EQUAL 14.318 FEET ON A RIGHT TRIANGLE BUT I AM TRYING TO REMEMBER HOW TO FIND MY ANGLES OTHER THAN THE ONE THAT IS 90 DEGREES.
The area of a triangle 2003-12-01
From A student:
Find the Area of Triangle ABC
A(-3,2)
B(4,0)
C(0,8)

Room and board fees 2003-11-29
From Jennifer:
A certain university wishes to determine room and board fees for the next academic year. For the current year, the fee is \$3600 per student and 1800 students are living in the residence halls. Past data suggests that for every \$300 increase in the semester fee, 200 fewer students will choose to live in the dorms. There are also costs to the university associated with the residence halls. The fixed costs total \$2,000,000 per semester. the variable costs are currently \$1000 per student but will fall \$100 per student for each decrease of 100 students. Your task is to help the university determine the optimal fee. Assume linear relationships between the number of students and the fee and between the number of students and the cost per student
5.75 acres of land 2003-11-28
From Susan:

We own 5.75 acres of land here in El Paso Tx. Some one wants to buy all or some of our land...to build homes on...but.. I can't figure a few things

1. our land is Almost exactly 500x 500x500 x500 ft square proprty based on this can you tell me the approx perimiter measurements of EACH acre we wish to sell approx 1/2 of this 5.75 acres ...or a tad bit less.. these are all approx measurements what I also need to know is.. how many 50ft x 100ft lots are in each (1 )Acre???

A fish tank 2003-11-26
From Bill:
How do I work out the volume and weight of water in a fish tank that is 36in x 14in x 12in?
Mr.Carter is very cautious 2003-11-26
From Bob:
Mr.Carter is very cautious. He decides to invest in only three stocks: one low stock, one high stock, one medium stock. Given that the expected annual yields are 6% for low stock, 7% for medium stock, and 8% for high stock, he wants his investment in medium stock to be half of his total investment in low and high stock. How much should I invest in each type fo stocks to expect a total annual return fo \$650 form my investments?
Area of an equilateral triangle 2003-11-25
From Jared:
Can you help me understand why the area of a equilateral triangle is the square root of 3 divided by 4 times the lenght of the side squared?
An inequality whose solution is all points 2003-11-25
From Katie:

Hi my name is Katie and I am in the 9th grade and I would like help on this question. Is it possible to have a system of inequalities whose solution is all points?

1.I need to know why (explanation)

2.how to do it(example)

The volume of an irregular tetrahedron 2003-11-24
From Peter:
How do I calculate the volume of an irregular shaped tetrahedron where:-
side a = 1.4 m
side b = 1.4 m
side c = 1.2 m
and height = 0.75 m at the junction of sides a and b.

Markup, profit and margin 2003-11-24
From Ali:
I have question regarding Margins, Markups and Profit Purchase price = \$ 10.00
Margin or Markup ?? = 40 %
Therefore Selling Price = 10/0.6 = \$ 16.67
Profit ? = (16.67-10)/10 *100 = 66.67%
or is the profit = (16.67-10)/16.67*100 = 40 %
Can you please clarify What is Margin, Markup and Profit

Difference of squares 2003-11-24
From Susie:

Factor assuming that n is a positive #

Problem: (I will give it to you in words beacuse I don't know how to do exponents on the computer.) Forty-five r to the 2n power minus five s to the 4n power. I was hoping you could walk me through it not just give me the answer.

An octagon shaped bed frame 2003-11-23
From Trish:
My son and I are making an octagon shaped bed frame. We are going nuts trying to figure out what angle to cut the boards to make an outline of an octagon. It seems that the 8 inside angles of the 8 "corners" are 120*, but what is the angle that the 2x6 wood should be cut so that they will angle together to form the outline of the octagon?
Laws of sines and cosines 2003-11-23
From A parent:
On the one side of a stream lines PA= 586.3 feet, PB = 751.6 feet are measures, angle APB being 167 degrees and 36 min. Q is a point on the opposite side of the stream. Angle PAQ=63 degress and 18 min and PBQ=49 degrees and 24 min. Find PQ.
The volume of a cube 2003-11-22
From A student:
i have a cube, and the line that cuts threough the middle of the cube across to the other side is 4 radical6. what is the volume of the cube?
Aristotle 2003-11-21
From John:

I would like to know how aristotle was related to math.

In all my searches I have found only philosophy etc. But not any math.

AB/AP=AP/PB 2003-11-20
From James:
My name is James McBride. I'm having a difficult time with a pre calculus problem, which goes as follows: "show that AB/AP=AP/PB is equal to (1+5^1/2)/2 (one plus the sqaure root of five with the sum divided by two. I can't do the square root sign, sorry.) I have tried to solve for PB in terms of the other varialbles and then work the quadratic equation. THAT DOES NOT WORK!!!! I am befuddled. Please help me. I am a student of secondary level.
Four digit numbers 2003-11-20
From Rob:
Hello, I sure hope you can answer this question. I got into a discussion at work about how many possible combinations there are for a four digit number using the numbers 0 through 9. This was in reference to a discussion about the lottery. I said there was only 10,000 possible combinations. My friend said that there was many times more, but he could not remember how to figure it out. The answer and the formula would be greatly appreciated.
962 Sq. Ft. is what percent of 2656 Sq. Ft 2003-11-20
From Jon:
962 Sq. Ft. is what percent of 2656 Sq. Ft
4(r-2) = r(2+8) 2003-11-20
From Angela:
I not going to give you the problem that I have, but a problem like it. 4(r-2) = r(2+8) I get mix up trying to solve a problem like this could you help me. So that I will be able to handle the ones on my homework.
A riddle 2003-11-19
From Sarah:
Ok, our teacher gave us this riddle, and I cannot for the life of me figure it out. He said that there are three problems with the following proof:
Systems of equations 2003-11-19
From Scott:

I hope that u can help me....I am a college student taking a class in Pre Calculus.....I have homework due this Friday and it counts a BIG Percentage on my FINAL grade.....I am getting mixed up and can not figure out a few problems.....Please help me.....

Method Of Subsitution

Problem 1. y- 8x = -5
x(squared) + y(squared) = 25

Problem 2. y = x(squared) - 2x - 6
Y = x(squared) - 4

A point and a line 2003-11-19
From Meenakshi:

Given a line segment L(x1,y1) to (x2,y2) and a Point P(x3,y3).
I need the formula to find a point on the line L that is closest to the point (x3,y3).

If 1 is neither prime nor composite... 2003-11-19
From Joshua:
if 1 is neither prime nor composite...what is it called?
Answered by Claude Tardif and Penny Nom.
If 1 is neither prime nor composite... 2003-11-19
From Joshua:
if 1 is neither prime nor composite...what is it called?
Answered by Claude Tardif and Penny Nom.
Unmatched socks 2003-11-17
From Shannon:

i have 6 pairs of socks lying unmatched in my dresser drawer. Each pair is a differnt color (brown, black, red, yellow, green, purple) When i wake up in the morning, I randomly grab 2 of the loose socks and put them on without looking.

If two socks are randomly selected from the drawer, what is the probability that they match?

The 4th difference 2003-11-17
From Jack:
If i had a sequence which was the same at the 4th difference, aka difference to the 4th, like:

1 5 14 30 56 96 (sequence)
4 9 16 26 40
5 7 10 14
2 3 4
1 1

then what would be the set formulars to find out a, b, c, d, and e
as i know the equation has to be an4+bn3+cn2+dn+e

From Ken:
My name is Ken and I am taking my GED course for my High School and have not been in a class for 35 years. I am doing this for re-training. I am at the part about fractions. Here is an example that I am having trouble with.

1 3/7 + 4 2/3 + 11/21

They have no common denominators. Could you PLEASE help me. If you could send me a step by step explanation it would be greatly appreciated.

Three problems 2003-11-16
From Megan:
My name is Megan and I am a junior in high school. Our teacher gave us a few xtra credit questions and I need some help.
Divisibility by 7 2003-11-14
From A student:
how do you test a number to see if it is divisible by 7 or not?
Lines 2003-11-14
From A student:
What is a name that a group of lines pass through?
root24 = 2 root6 2003-11-13
From Burke:
I know that all algerbra can be represented visually, for example: Y=9x+3 is a line on a two dimentional plane. Could Math Central please send me a visual representation of the proccess of simplifying square root like root24 equals 2root6
Diagonals in an octagon 2003-11-13
From Glenn:
Question 1.
What is the probability of choosing the longest diagonal in an octagon?

Question 2.
Probability of choosing the shortest?
Answered by Andrei Volodin and Penny Nom.

A trig identity 2003-11-12
From A student:
(1-tanx)/(1+tanx)=(1-sin2x)/(cos2x)

What is a number that has exactly 13 factors? 2003-11-09
From Mary:
What is a number that has exactly 13 factors?
Mixing Brazil nuts and cashews 2003-11-09
From Bob:
Cashews are sold for 1.20 per 1/4 pound and Brazil nuts are sold for \$1.50 per 1/4 pound. If you mix 20lbs of Brazil nuts, how many cahsews would it take to make a mix that sells for \$1.30 per 1/4 pound?
A least squares line 2003-11-09
From Michelle:
Hooke's Law asserts that the magnitude of the force required to hold a spring is a linear function of the extension e of the spring. That is, f = e0 + ke where k and e0 are constants depending only on the spring. The following data was collected for a spring;

e: 9 , 11 , 12 , 16 , 19
f : 33 , 38 , 43 , 54 , 61

FIND the least square line f= B0 + B1x approximating this data and use it to approximate k.

Greatest Common Factor 2003-11-08
From Beth:
How do you use the Greatest Common Factor in addtion and subtraction of fraction?
Equal ratios 2003-11-07
From A student:
In the ratio 3:8=17__, can__be a whole number?
The product of the page numbers 2003-11-07
From Morgan and Mom:
You open a book and the product of the page numbers is 12,656. What are your page numbers?
Chisenbop 2003-11-06
From Jaclyn:
Hi there i was wondering if you would have any information on "counting on your fingers" or " Chisabop".
Intercepts 2003-11-04
From A student:
I am totally confused on how to determine intercepts of an equation and then to graph the line. For example, how to determine the intercepts of 2x-3y-12=0.
X bar 2003-11-04
From mary:
Remind me what this means:

```    _
X
```

The length of a chord 2003-11-03
From David:
When Radius=400.00' and Arc=130.58' what is the Cord distance in feet?
A circle around an irregular polygon 2003-11-03
From Dale:
How do I find the properties of a circle that is drawn around an irregular polygon of (n) sides with the lenghts of each side given and all end points of the polygon lye on the circumferance of the circle?
Solve for Q 2003-11-03
From Anwaar:

The problem is:

QT - X
________ + H = HT
QS

Cubic yards of concrete 2003-11-02
From John:
The foundation is 20' X 20' and the depth is 6", there are also three footings that are 20' X 12" X 12" each. Can you show me the equation to figure out how many yards of concrete I will need to pour the footings and foundation.
Symmetries of a rhombus 2003-11-02
From Tonia:
why cant an equal sided rhombus have 3 lines of symmetry? you have one line of symmetry on each of the diagonals, and there should be one vertically on an angle. can you please explain the rules of symmetry to me?
Which one has the most factors? 2003-10-31
From Kristi:
Of all the whole numbers less than or equal to 5000, which one has the most factors?
Divisibility by 2 or 5 or both 2003-10-30
From Abdu:
How many positive integers less than 1,001 are divisible by either 2 or 5 or both?
1/x + 1/y = 5/12 2003-10-30
From Ben:
1/x +1/y =5/12, what is the sum of x and y?
From Joel:
there are 12 chocolate, sugar and cinnamon cookies. the probability of choosing a chocolate cookie is 1/3. the probability of choosing a sugar cookie is 1/4 what is the probability of choosing a cinnamon cookie
A rectangle on a disk 2003-10-29
From Arthur:
How do I go about solving the following problem: What is the width of the largest rectangle with a length of 16 inches you can cut from a circular piece of cardboard having a 10 inch radius?
How much time? 2003-10-29
From Lori:
I am a elementary teacher 3-6 math. We have just implemented the Houghton Mifflin Math curriculum. It seems to be quite difficult for most of our students. In order to get through all the material we need to do a lesson a day. Although the students are not getting the material that fast. Should we move on without all the students understanding the material or should we wait and remediate until they get it and be behind for the year. This isn't just a few kids its most of the kids. We are also suppose to teach to all the standards so if we don't get to them the students will not do well on the standardized tests.
Trees 2003-10-28
From Ali:
Is there any formula for counting the number of trees (graphs)?
Means 2003-10-28
From Abdu:

Question:
80,80,84,85,88,92,97,98

The average of the 8 numbers listed above is 88. Of the following which pair of numbers could be removed from the list without changing the average.

A. 80 and 97
B. 80 and 98
C. 84 and 92
D. 84 and 97
E. 85 and 92

Answered by Andrei Volodin and Penny Nom.
Solve for x 2003-10-27
From Lonnie:
i need help with solving equations and formulas such as -3x+b=6x, for x. I do not understand how you find x.
Knitting gauge and felting 2003-10-27
From Sara:

I wish to create a pattern to knit an item that will then be felted, thus, shrink as a result. In order to determine the proper gauge to use in creating the item, I produced a gauge swatch, noted the original properties and then the post-felting properties. They are as follow:

Before Felting:

20 stitches(width) x 20 rows(height)yielded:
Gauge: 3.2 stitches(width) and 4 rows(height) = 1"
Dimensions: 6.25"(width) x 5.25"(height)

After Felting:

20 stitches(width) x 20 rows(height)
Dimensions: 4"(width) x 3"(height)

How do I calculate the percentage change in size to accurately determine the number of stitches and rows needed to produce the desired dimensions for the finished (felted) item?

A rock on a string 2003-10-26
From A student:
a rock on a 4' string is rotated at 80 rpm. what is the linear speed in feet per second? in miles per hour?
From Jimmy:

From 1989 to 1990, the population of Nevada increased b y 157,000, and that of Maine increased by 30,000. In 1990, the population of Nevada was 1,206,152, and that of Maine was 1,233,223. If the populations of the two states continue to increase at the same rates, when will the populations of Nevada and Maine be the same?

Write a verbal model for this problem
Write an equation for the model
Solve the equation and answer the question.

A parabola 2003-10-24
From Delores:
Given the vertex (4, -2) y intercept = -6 find if/where the parabola crosses the x axis?
0.810 and 0.801 2003-10-24
From Ahmed:

could you please tell me what is the greatest decimal fraction formed of the digits 0, 1 , 8?

Is it 0.810 or 0.801, please give me the reason of the answer in details and the references if it possible.

Odd Pythagorean triples 2003-10-23
From Kathleen:
in a triple can a and b be odd numbers
Arithmetic in bases other than 10 2003-10-22
From Kim:
how do you add, subtract, multiply and devide in base 3, base 5, etc?
Squares in a rectangle 2003-10-21
From Raj:

Draw a rectangle with sides of 3 and 4. Divide the sides into 3 and 4 equal parts respectively. Draw squares joining the points on the sides of the rectangle. You will have 12 small squares inside the 3 x 4 rectangle.

If you draw a diagonal of the rectangle, it will intersect 6 of the the 12 smaller squares.

Similarly, if you have a 4 x 10 rectangle, the diagonal would intersect 12 of the 40 squares inside the rectangle.

Is there an algebric equation that determines the number of squares that will be intersected by the diagonal of a rectangle?

0.3 trillion 2003-10-20
From Bill:
What is .3 of one trillion?
Domain of a function 2003-10-14
From Karim:
Find the Domain of the Function
H(x) = Log3 (4x + 7)-10
H(x) = log base 3 times 4X plus 7 minus 10
i am having problem solving these kinds of problems.

Pairs of prime numbers 2003-10-13
From Nikolas:
Use pairs of prime numbers to find all the numbers less than 50 that have only two prime factors. Make an organized list.
5x - y 2003-10-11
From Candace:
math problem 5x-y for x=12 and y=14 do you mulitilpy 5x12 and than -the answer from 14 which gives you 46? is this right
Points inside a triangle 2003-10-10
From Laura:

is there a way to establish, if a given point at coordinates (x,y) is within an area defined by three other sets of coordinates forming a triangle ABC?

is T(x,y) within triangle A(x,y)B(x,y)C(x,y)

Statistics from grouped data 2003-10-09
From Rebecca:

I have to use a suitable computer package (ie. Excel) to work out the mean and standard deviation of the following:

``` Price Range            No of Houses        No of Houses
£`000                  Area 1              Area 2

45 and under 50         4                   5
50 and under 55        7                   12
55 and under 60        14                  16
60 and under 70        19                  18
70 and under 80        8                   3
80 and under 100       5                   2
```

I have used excel to work out mean and standard deviation before, but not in a more complicated example like this.

Any advice on where to start would be greatly appreciated.

10,000 2003-10-08
From Nathan:
what two numbers make the product of 10,000. Neither number can end in a zero
Interest compounded daily 2003-10-08
From Terie:
If I owe \$2000.00 @ 6.25% compounded daily for 54 days. How much do I owe in interest?
Standard Deviation 2003-10-07
From Rebecca:

I have a task to complete, which is to calculate the mean and standard deviation of something. I have done this but am then asked to write a short explanation of my findings.

I know what the mean is about, and I thought I knew what the standard deviation meant too - shows the variation from the mean. However, on a task I completed earlier the feedback I got said 'you need to tell us that it is talking about the middle 66% of the data' - that has thrown me, I don't understand that. Can anyone help me get my head round this???

Two chords 2003-10-07
From Lori:
Chords AB and CD of circle O intersect at E. If AE=4, AB=5, CE=2, Find ED.
The sketch of a graph 2003-10-07
From A student:
I was wondering how do you figure out if a graph has a horizontal tangent line. One of my homework problem was to sketch the graph of the following function; (4/3)x3-2x2+x. I set f''(x) ( the second derivative) of the function equal to zero and got the inflection point:(1/2,1/6). Also i am having trouble finding the concavity for x>1/2 and x<1/2, i am getting a different answer from the back of the book, the graph i draw looks completely different from the correct answer.
Arrangements around a circular table 2003-10-07
From Lori:
How many arrangements can 6 people be seated round a circular table?
Indeterminate forms 2003-10-06
From A teacher:
Is it possible for me to find any geometrical interpretation without using calculus to explain indeterminate forms?
Functions, graphs and derivatives 2003-10-05
From Jathiyah:
I wanted to know how would you tell (on a graph diplaying two funtions), which funtion is the derivative of the other?
The slope of a tangent 2003-10-01
From A student:

find the slope of the tangent to each curve at the given point

f(x)=square root 16-x, where y=5

A rectangle in a circle 2003-09-27
From Abdu:
A rectangle ABCD is inscribed in a circle. If the length of AB is 5 and length of BC is 12, what is the area of circle outside the rectanlge ABCD?
Relatively prime 2003-09-27
From James:
what is the definition a relative prime numbers?
0/0 2003-09-25
From Thomas:
How is 0/0 ever defined.
Absolute value 2003-09-23
From Crystal:
I am trying very hard to understand Absolute Value, and I cannot seem to grasp the idea. I do not know why we use it, what the point of it is. I do not know how to use it. I know that it is always positive or zero, and I assume it relates to distance, but how can you use it in equations. Please explain it to me as simply as possible, thank you.
The golden ratio 2003-09-23
From Phillip:
The Golden Section can be made from an equilatereral triangle inscribed within a circle. The Golden Section is achieved by joining the mid points of two arms of the triangle to the circumference. I can prove this by erecting a perpendicular to the line outside the circle, but am interested to see how it can be proved from within the circle.
Primes 2003-09-23
From Julie:

#1. Suppose you are given a number (n) and told that 1 and the number (n) divide into (n). Does that mean (n) is prime?

#2. Suppose that p is a prime number greater than or equal to 3. Show that p+1 cannot be a prime number.

The Sieve of Eratosthenes 2003-09-18
From Lynn:
My daughter has been asked to find all the prime numbers by using the Sieve of Eratosthenes. I have no understanding what this means.
Answered by Penny Nom and Claude Tardif.
1 + 1 = 10 2003-09-17
From David:
could you please explain to me how 1+1=10 thanks
Applications of logarithms 2003-09-16
From A student:
I have a project due in my algebra two class dealing with logs and where they are used in life, but I am having trouble finding websites that relate. So I would really appreciate it if you couldhelp me.
Notation 2003-09-15
From Kim:

Question:
i have a couple of questions

1. write in standard form
a)4x2x8 b) 5 to the power of 4

.
.
.

Substitution method 2003-09-14
From John:

Hello, my name is john and while I was finishing up my work I stumbled into these problems. a/4-b=-1
a+b=11
and
6a-b=-5
4a-3b=-8

Thanks a lot. I really need some help :)
John

The volume of an earthen pit 2003-09-12
From Bruce:
This shape would occur at the four corners of a rectangular shaped earthen pit with sloping sides (1:1.5). Depth is 14'. Top dimensions are 170' by 158'. After calculating the easy volume components of this shape, we are left with the end corner pieces. 21' base, 14' height, side hypotenuse 25.24' and corner diagonal 32.83'. We're confused. Thank you for any help you may provide.
The digits in 349 2003-09-12
From Franik:
in the number 349, which number has the least value, and why?
Two line segments and a plane 2003-09-11
From Laura:
Do all figures made up of two segments lie in a plane?
Area of a rectangular room 2003-09-11
From Kelly:
The area of a rectangular room is 238 square feet. The width is 3 feet less than the length. What are the dimensions?
The general equation for a sphere 2003-09-11
From Jaidev:
Is there any general equation for a sphere?
The mean house price 2003-09-10
From Carol:

Question:
I have to find the mean from the following example:

Price Range £000 No of Houses
55 and under 60 3
60 and under 65 6
65 and under 70 13
70 and under 80 21
80 and under 100 15
100 and under 130 7
130 upwards 1

I know when calculating the mean you use the mid points of the classes, but how does this work for the 130 upwards class? Also, does this still work given the difference in the classes (ie. 1st class is 5, 5th class is 20, etc). Any help to get me started would be greatly appreciated.

Converting from base 10 to base 5 2003-09-10
From Susy:

My son, who is 9 in grade 5 has been asked to convert base 10 numerals into base 5.

His first question of:

24(10) he has calculated to be 4x5 + 4x1 = 44 (5)

The next question however is the tricky one.Ý We know the answer is supposed to be 100 but we find it difficult to get this in the way he understands it.

25 (10) = _________________ 100 (5)

Can you help us figure out how we reach the answer.

Answered by Claude Tardif and Penny Nom.
How high does the sequence of numbers go 2003-09-07
From Shayna:
My quetion is "How high to the sequence of numbers go"?
e.g. one, ten, hundred, thousand, million, billion, trillion, and from there is my queston.

Making a square 2003-09-07
From A student:
if I am given any number (say 80 for example), how may I determine the smallest whole number integer which when multipled by it will yield a square number ? In other words if I express this as: 80Ý*ÝnÝ=ÝsquareÝnumber, what is the least value of n which will yield a square.
Consecutive integers 2003-09-07
From Amy:
I was wondering if there was a proper way to write the solution to a problem requiring consecutive integers? Is it okay to write the solution as 5,4,3,2,1 or must it be written as 1,2,3,4,5?
Order of operations 2003-09-07
From Brian:

It has to do with the 4 rules of operations, Parentheses first before operations outside/evaluate all exponential expressions/all multiplication and divisions/then all additions and subtractions.

Who made these rules and when did they make them,,, I know its somewhat of an unorthadox question but I must know. I would really appreciate it.

7,473,000,000 divided by 52000 2003-09-06
From A student:
I am having trouble with a question. 7,473,000,000 divided by 52000. Our calculater gets 147311.5385. I come up with 143711.53846, and then the number starts to repeat itself
Can 2 vertical planes intersect? 2003-09-06
From Erin:
My question is can 2 vertical planes intersect?
One million seconds 2003-09-04
From Vince:
If you can write a number each second for one million seconds, how many hours would it take?
Four digit combinations 2003-09-04
From Emma:
I seriously need to find out all the four digit combinations from 0 to 9!!! My name Is Emma Dibitt and I'm going into 8th grade and I'm a student!!!
Grooming the king's horses 2003-09-04
From Janelle:
the stable boy had 90% of the kings horses groomed.the next day the king acquired 25% more horses. Now there was 105 horses not prepared for the kings men. How many horses did the king originally have?
From Kelly:
Two buildings are separated by a three-foot alleyway. Fatima wants to use a 16 foot ladder to reach a window in the wall of one of these buildings. If she places the foot of the ladder against the base of the other building, how far up the wall will the top of the ladder reach??
One percent of a billion 2003-09-04
From Charles:
What is one percent of one billion?
Positive, negative and zero 2003-09-04
From Brian:
Can the Value of zero be positive or can it be negative or can it be both.
The game of 24 2003-09-03
From A student:
We have a game where four numbers must equal 24 using addition, subtraction, multiplication and/or division.Ý I am stuck on the following four numbers - 12, 24, 9 and 17.
A boat travels 12 km upstream... 2003-09-03
From Sohaib:
A boat travels 12 km upstream and back in 1 hour 45 minutes. If the speed of the current is 3km/hr throughout, find the speed of the boat in still water, giving your answerÝcorrect to 3 decimal places.
Why percentage? 2003-09-03
From Vicky:
My cousin aske me a question about the use of percentages and I'm not sure how to answer it. He wants to know why when there is a sale in a shop we use percentages and not fractions or decimals.
Percentage markup 2003-09-03
From Virginia:

I am confused and hope you can help. I have looked high and low for a "chart" persay to go by when I am having to calculate markup percentages.

Example if I have a List price of \$1838.00 and my cost is \$955.76 and I want to mark it up 30%. My colleage says it should be divided by .7

I don't understand how he arrives at .7 from 30 percent.

Profit margin 2003-09-03
From Chet:

My salesman calculates a customers profit margin by dividing what the customer paid by what he sells for, then subtracting that answer from 1. For example a customer sells a product for \$15. He bought it for \$10. 15/10=.66 Subtract that from 1 and get a profit % of 33%

Here's my question: If I want to figure what a reseller will sell a product for if he wants 40% margin(by the technique above), what formula do I use? Let's say I want to sell a product for 8.50, and I want the reseller to make 40%

Two row arrays 2003-09-03
My question is, what are #'s that can not be arranged in two row arrays called?
A helicopter rises vertically 2003-09-02
From Kate:
A helicopter rises vertically and t seconds after leaving hte ground its velocity is given in feet per second by v(t) = 8t + 40 / (t+2)2 How far above the ground will the helicopter be after 3 seconds?
Water in a tank 2003-09-02
From A parent:
if a tank is 48 inches long 14 inches wide and 18 inches deep if a yardstick was inserted into the tank and measured 2 inches of water in the tank how many gallons of water would be in the tank.
A theorem in geometry 2003-09-02
From Diego:
Please refer to figure in attached file. P is a point on the chord AB of a circle such that the tangent PT which touches the circle at T is equal to AB. How do we prove that PT2 = AP x BP.
Answered by Dieter Ruoff and Penny Nom.
The units digit of 57 to the 28th power 2003-09-01
From Maria:

If 57 is raised to the 28th power, what must be the units digit in the result?

If you raise 7 to the 500th power, what is the numeral that will appear in the units digit position?

A 6 team schedule 2003-08-31
From A scheduler:
I saw that someone put on your web site a team schedule and you helped them figure it out.Ý I have 6 teams that want to play each other once, and believe it or not, I cannot figure it out.
20% of 40% of 500 2003-08-31
From A student:
What is 20% of 40% of 500?
Terminology 2003-08-31
From Maria:
My daughter Veronica is a rising 6th grader and has to complete some Summer Math
assignments and would like to ask you three questions:
1. ___________ are number pairs that have a product of 1.

2. You can name any point on a plane with two numbers. These two numbers are called _____________.

3. A _______________ is the size of a cube that is exactly 1 inch on each edge.
Thanks,

From Alex:
I am using Houghton Mifflin's Precalculus with Limits book, 2nd edition. However, the first chapter encompasses Algebra review, and I am stuck on a problem. All that's required is to solve the following and verify using a calculator:
3y2+6y+2=0
I have solved the problem using the quadratic formula, but from what I remember, the quadratic formula is used in the case of equations following the AX2+BX+C=0 pattern. As the problem I am attempting uses a y-variable, can I still use the quadratic formula? Since I am not sure what route to take in solving this problem, I am hoping you can assist me.

Newton's binomial theorem 2003-08-30
From William:
According to page 126 of Murtha & Willard's "Statistics and Calculus" (Prentice-Hall, 1973), Newton's binomial theorem can proved inductively. I suppose that was his method, which I would like to see.
I can Guess your birthday 2003-08-29
From Michelle:
Hi I am trying to explain to my children how this problem works. It was sent to me on the internet and I can not figure it out. They keep asking me how it works and I can not tell them.

The problem is: "I can Guess your birthday::

How many cubic yards must I purchase? 2003-08-29
From Walt:

I am trying to determine how much top soil I must purchase (by the yard).

The area is 80' x 15' and I want it 3" thick. How many cubic yards must I purchase?

Converting to base 10 2003-08-28
From Karen:
My son is in 5th grade.Ý He is learning how to convert numbers from base 2 to base 10, and base 5 to base 10.Ý Can you explain it to me in the simplest terms?
Graphing a piecewise function 2003-08-24
From Amber:
How do i begin to graph a piecewise function, absolute function or step function?
Simplify 2003-08-24
From Jessica:
I have been asked to simplify the expression (5a2)(-2b2)(3b)+(7a2)(2b2)+(-3a)(-5a)(4b) and the answer is apparently 44(a2)(b2). For the life of me I can't figure out how they derive this.
Why is 5 to the 0 power always 1? 2003-08-24
From Crystal:
Why is 5 to the 0 power always 1?
A rule with a variable 2003-08-24
From Crystal:
what is a rule with a variable
X.9999... and X+1 2003-08-23
From David:
I have read your answers to the questions on rational numbers, esp. 6.9999... = ? and still have a question: The simple algebraic stunt of converting repeating decimals to rational numbers seems to work for all numbers except X.999999.... where X is any integer. The fact that the method yields the integer X+1 in each case seems to violate the completeness axiom of the real numbers, namely that there is no space on the number line which does not have an number and conversely that every geometric point on the number line is associated with a unique real number. In the case of 3.999... for example, it seems that both the number 4 and the number 3.9999.... occupy the same point on the number line. How is this possible???
A golf tournament 2003-08-23
From Dale:
I am running a golf tournament with twelve golfers. We will be playing four rounds of golf. I don't want to schedule the same two players together more than twice (if possible). How would I make a schedule that each player would play at least once with every other player? I would appreciate any help that you can give me.
A worm on a hill 2003-08-21
From Lisa and Samantha:
A WORM IS AT THE BOTTOM OF A 10 FOOT HILL. HE CRAWLS UP THE HILL 4 1/2 FEET A DAY. AT NIGHT WHEN HE REST HE SLIDES DOWN 2 1/2. HOW LONG DOES IT TAKE THE WORM TO CRAWL UP THE HILL.
Two equations 2003-08-21
From Jennifer:

The following problems have me stuck and any help would be greatly appreciated seeing my text book is doing me no favours:

32a+1 - 283a + 9=0
and
52m - 5m=20

39 consecutive natural numbers 2003-08-19
From A student:
Prove that among any 39 consecutive natural numbers it is always possible to find one whose sum of digits is divisible by 11.
The volume of a fuel tank 2003-08-16
From Phil:
I hope you can help me out with a small problem. My boat has a fuel tank measuring 1680mm long x 630mm wide x 130mm high. Can you tell me how much fuel it will hold in both litres and imperial gallons.
The number of three digit combinations 2003-08-16
From Fred:
There are four close friends having a heated discussion concerning the the number of three digit combinations using the numbers 0 through 9. The discussionÝinvolves the daily lottery.Ý Any assistance you can lend would be greatly appreciated.
Acres 2003-08-13
From A landowner:
Can you please tell me how many total acres the following measurements would equal? 280 feet by 80 feet
220 feet by 70 feet
200 feet by 75 feet

Making a blanket 2003-08-13
From Liz:
Please help me figure this out. I am making a blanket the directions call for a piece of material measuring 72"X45". Instead of one piece I'd like to make a patchwork quilt but the squares need to equal 72"X45". Centered on the bottom of the longest edge is an 18" square.
Water in a cone 2003-08-12

Water is poured into a tank in the shape of an inverted right circular cone.ð The height of the tank is 8 m and its radius at the top is 4 m.

a. Draw and label a picture to represent this situation.ð (I know how to do this)

b. Identify all variable quantities. (h = 8m, r = 4m)

c. Find an equation that relates the variable quantities, and reduce the number of variable quantities to two.

I was thinking about the equation V = 1/3 pi r2 h, which is the Volume of a cone, but I am stumped as to how I am supposed to "reduce the number of variable quantities to two." Can you point me in the right direction?

Yards and cubic feet 2003-08-11
From Sonya:
How many cubic feet are in a yard?
A sphere inscribed in a cone 2003-08-10
From A student:
A sphere with radius 5cm is inscribed in a right circular cone 20 cm in height.find

(a) the base radius ,volume of the cone
(b)volume of the shaded space( to 3 sig fig)

The side length of a regular octagon 2003-08-09
From Rich:
If I know the distance between the parallel lines of an octagon and want to find the length of the sides, can I just divide that distance by 2.414 to reveal the length of the sides? I work construction and just curious if I am figuring it right.
Liters in a pool 2003-08-05
From A parent:
I need to know how many litres in a 12 foot diameter, 3 foot deep pool? Any help much appreciated as I need to add the correct amount of chemicals
Diagonals in an octagon 2003-08-04
From Amanda:
How many diagonals are in an octagon??? What would be a drawing of those diagonals???
Two precalculus problems 2003-08-04
From Kate:

cos2x(sec2x-1)=sin2x

Also I am having trouble withdetermining whether f(x) is odd, even, or neither
f(x)=x3-x

The incline of a road 2003-08-03
From A driver:
incline- % grade as to degree. ie 6% hwy grade= what degree of incline?
Percentage decrease in sales 2003-07-31
From Linda:
If I had sales in January of 2002 that were \$42,493.73 and sales that were \$37,281.59.Ý The difference is \$5374.50.Ý What is the percentage of decrease in sales?
Inserting a comma ever three digits 2003-07-25
From Linda:
when writing a large number, why do we insert a comma every three numbers instead of every two or four numbers?
Cutting some wood 2003-07-25
From Betty:
My husband is building a six sided wood circle and would like to know the angle to cut the pieces.
The area of an odd shaped piece of property 2003-07-24
From Barry:
What is the formula for figuring the square footage of an odd shaped piece of property?
Surface area of a sphere 2003-07-23
From Rob:
I have a shere with a circumference of 12 feet. What is the total surface area of the shere in square feet and how did you find it?
nine digit numbers 2003-07-23
From John:
With a nine digit number, with each of the nine digits having a possibility of 10 different numbers then what is the total number of possible mathematical variations in the nine digit number. i.e. Social Security numbers have nine digits and if each of the nine digits have a possibility of being any one of ten numbers, i.e. 0,1,2,3,4,5,6,7,8,9. Then what is the formula to calculate the maximum possible number of variations in this nine digit number and what is the mathematical maximum possible number of variations of this nine digit number?
Natural logarithms 2003-07-22
From Amanda:
I'm going into my senior year of high school. I will be taking AP calculus, and my teacher gave us some homework over the summer. However, there are two things that I do not understand how to do. The first is, she wants us to be able to generate a unit circle by hand using 30, 60 and 90 degree triangles. I have used the unit circle in trigonometry, however I was never taught how to draw it. Secondly, I need to know how to do natural logarithms without a calculator. I was not taught how to do this, and the worksheet I was given only showed me how to complete them using a calculator.
A pyramid with its top cut off 2003-07-21
From David:
What is the name given to a 3D shape that looks like a pyramid with its top cut off?
Slope 2003-07-20
From Brian:

You are placing a pipe 60 feet long at a slope of 1.5%. How would you figure the amount of drop from the inlet of the pipe tot he outlet of the pipe? and what is the answer .

If you are trying to keep a shoulder slope of a road between 3/4'' per foot and 11/2'' per foot . If the shoulder is 10 feet wide, how would you figure how much lower should the outside of the shoulder be than the edge of pavement and what is the answer ?

|x+3| = -15x 2003-07-19
From Nathan:
Without the use of trial and error, is there a way of solving for x where |x + 3| = -15x? I know that x = -0.1875, but how do I find whether x + 3 is positive or not if I did not have this information (In other words, how would I solve whether the x-value was -3 or less, or if it was more than -3)?
Answered by Claude Tardif and Penny Nom.
"cubic feet" of a refrigerator 2003-07-16
From Ron:

Is the volume of a home appliance (e.g. fridge or freezer) calculated in a different way? I am planning to replace both my fridge and my freezer but I'm unable to determine what size replacement to get.

For example, one company descibes their fridge as being 32"(L) x 30"(W) x 66" (H). I converted those measurements to feet (2.67 x 2.5 x 5.5) and I calculate the fridge to be 36.7 cubic feet. However, the company says the fridge is 18 cf.

Cathy's Clothing 2003-07-15
From Cathy:
I am supposed to write a practical and useful word problem that would use the following algebriac inequality to solve it: 12x + 25 > 15x + 10. State the quanity that represents x and solve the inequality.
Preparing 100ml of a 30% alcohol solution 2003-07-13
From Justin:
My question is how do you prepare a 100ml of a 30% alcohol solution using 95% alcohol?
Sunshine? 2003-07-11
From lori:
It is noon, your lunch hour, but you cannot go out because there is a terrific hailstorm. Turning on your radio you hear the weathercaster predict that the hail will change to rain and that it will pour all day today. How can you determine whether the sun will be shining in 36 hours?
A problem with lugs 2003-07-11
From Lori:
A young man's car developed a flat tire as he was driving along a deserted street. He pulled over to the curb and did all the usual things: removed the hub cap, unscrewed the lugs and rested them carefully in the hub cap, jacked up the car. As he was putting the spare tire onto the axle he accidentally kicked the hub cap. The lugs rolled out, and all five of them fell down a nearby grate. Peering through the bars of the grate the man thought that he could see the lugs about 6 feet below in a shallow water puddle. He had a problem. How do you think he solved it?
A mixture problem 2003-07-10
From A student:
Having a problem with word problems. example A chemist mixes a 10% acid solution with a 50% acid solution to form 400mL of a 40% solution. How much of each solution should be used.
A triangle in the complex plane 2003-07-10
From Scott:
The vertices O and A of an EQUILATERAL triangle OAB in the complex plane are located at the origin and 3 + 3i. Find all possible values for the complex number representing the vertex B. Give the location of B in both polar and cartesian form (to 2.d.p)
E(X + Y) and V(X + Y) 2003-07-10
From Reuben:

I'm a teacher trying to find a way to make some stats work from first principles. The topic is expectation algebra and it is for the top age level in high school.

By using a set of data I can show how the mean is the same as the expected value ie 2,2,3,4,4 is 15 / 5 = 3 also, 2x0.4+3x0.2+4x0.4=3. I can also show this to work for the variance in the same style but using Sum(x-mean)2/n and the Var(X) version of squaring x then multiplying by the probability ( all this for random independant samples).

Now comes the tricky bit.....when I try to show E(X+Y) = E(X) + E(Y) from setting up two data sets I get it to work only if I add each item from X to each item from Y. However, I can't get it to work for V(X+Y)=V(X) + V(Y) from two sets of data.

There must be something missing in my knowledge of how the sets are required to add together or my knowledge of expectation algebra. I am familiar with proofs but still want to show my students that the basic formulae work from groups of data whether done the long way or by use of formulae. Can you help please?

An onsale DVD player 2003-07-09
From Kim:
I have a DVD player with a regular selling price of \$175 and percentage of discount is 10 percent. How to solve for discount amount and sale price? Also, when you figure out the sale price how to figure out commission amount when percentage of commission is 5 percent?
A wooden deck around a pool 2003-07-09
From Dat:
A pond is enclosed by a wooden deck that is 3 feet wide. The fence surrounding the deck is 100 feet long.
1. If the pond is square, what are its dimensions?

2. If the pond is rectangular and the length of the is three times its width, what are the dimensions of the pond?

3. If the pond is circular, what is the diameter of the pond?

4. Which pond has the most area?

Two cars 2003-07-09
From Nicole:
Two cars start off at the same point on a striaght highway facing opposite directions. Each car drives 6 miles, talkes a left turn, and drives for 8 miles. How far apart are the two cars.
Is 3/5 CLOSEST to 0, 1/2 or 1? 2003-07-09
From A student:
I would like to know is 3/5 CLOSEST to 0, 1/2 or 1. And can 3/10 go either way as to be closest to 0 or 1/2.
A geometry problem 2003-07-08
From Chris:
My name is Chris, I work for a custom fabricator company. I am needing a formula for the Height (H) shown in the attached picture. The picture shows dimensions for my current application. If you could please, assign variables to the dimensions.
Volume of water in a pool 2003-07-06
From An other:
How many litres of water are in a pool that is 16 feet in diameter and 35 inches deep?
The length of fabric in a roll 2003-07-03
From Paul:
We receive rolled fabric as part of our process and I would like to know is there a formula that could be used to estimate the overall length of the roll with out rolling the fabric out and measuring its length.
Contradiction in the Procedural Precedence and the Distributive property 2003-07-03
From Arthur:
When complicated expressions exist on both sides of a fraction, and both these expressions contain like and unlike terms with "literal" coefficients, the procedural precedence suddenly gets extremely confusing and seems impossible to simplify. This seems confusing and impossible to simplify because there is a HUGE contradiction in the way Procedural Precedence and the Distributive property deal with Parentheses. The Procedure says you MUST deal with what's INSIDE the parenthesis FIRST, BEFORE dealing with ANYTHING on the outside where as the Distributive property contradicts that by saying to go ahead and ignore the Precedence and use a factor on the outside of the Parenthesis.
C is 10 more then the square of... 2003-07-03
From Carolina:

C is 10 more then the square of the quotient of the sum of x and y , and the product of x and y. Which equation expresses this relationship?

```A. C=(x+y +10)^2        ___        xy
B. C=(x+y)^2 + 10        ___        xy
C. C=(xy)^2+10           ___       x+y
D. C=(x+y)^2 + 10        ___        xy
```

The domain of 1/g(x) - 5 2003-07-03
From Barbara:
If the range of g(x) is ( neg. infinity,4] and the domain of g(x) is ( neg. infinity, infinity), how do I find the domain of 1/g(x) - 5?
How much soil will be removed? 2003-07-02
From Amy:
My site is 1230' (east-west) by 1300' (north-south) and we need to remove 2 feet of soil from the entire site, how much soil will be removed?
Setting up a word problem 2003-06-30
From Christie:
A rectangular corral is forty feet longer than it is wide. If the perimeter is 220 feet, determine the length and width of the corral.
A ruler and compass construction 2003-06-29
From Mandy:
I have been searching for instructions on how to do this using a compass. Can you please send instructions step by step on how to bisect a segment into any given number of segments. (example, a way that it will work for bisecting segment into 3, 4, or even 5 congruent parts)
Solve x = y^z for z 2003-06-28
From Nathan:
If x = y^z is there a way to solve for z, if x and y are given, without guessing or already knowing the answer?

ie: 64 = 2^z
6 is the obvious value for z. Is there a way I could solve for this variable using a formula, which would also apply when more complex values were substituted for x and y?

Polynomials degree 4 and bigger 2003-06-26
From Stephen:

How do I show kids how to find all the zeros for polynomials degree 4 and bigger.

For examples:
r(x) = x5-11x3-7x2+77 = (x2-11)(x3-7) and s(x) = x4-121 = (x2-11)(x2+11)

Also am I correct when I say that the following are irreducible?

f(x) = x2-11
g(x) = x3-7
h(x) = x4-5

Odd powers of sine and cosine 2003-06-25
From Antonio:
Can you please tell me how to integrate a trig function involving sine and cosine? I know if the powers of both the sine and cosine are even and nonnegative, then I can make repeated use of the power-reducing formulas. But for the question I have on my hand, the powers of both sine and cosine are odd: ( sin3x + cos7x ) dx.
Sesame Street on Stage 2003-06-25
From Christie:
Sesame Street on Stage has different ticket prices for adults and for children under 6. Beth and her two children, ages 3 and 4, paid \$15 to gain entrance, while Jamie and John Jacobs and their 2-year old daughter got in for \$19.50. What is the ticket price for adults?
4-3(m+1)=(-38) 2003-06-25
From Jamie:

I have a problem, like most of your mailers, I do remember BEDMAS but maybe I'm missing the finer points!

It's been a while, he goes

4-3(m+1)=(-38)

Interest compounded daily 2003-06-24
From Jeff:
What would be the amount of interest charged or accrued and how is it calculated on principal balance of \$209.12 @ 6% interest rate compounded daily for 70 days?
pst and gst 2003-06-24
From Robin:
I need to find an easy solution to remembering how to calculated the gst and pst once I have the total amount. ex: my total is \$154.40, I have to find the gst and then the pst. I live in bc so the taxes are 7% for gst and 7.5% for pst.
Flim 2003-06-24
From Dan:
I have a 4th grader and the word (Flims) came up in her summer text,
An inch and a millimeter 2003-06-21
From Greg:
The conversion factor for inches to millimeters 25.4 It strikes me as very odd that it's not some infinite decimal. I could understand this if one system was derived from the other but as I understand it they were derived independently. Is the conversion 25.4 or 25.4000XXXXXXX? If it's just 25.4 then how did that happen?
Numbers John likes 2003-06-20
From Steve:
John likes 400 but not 300; he likes 100 but not 99; he likes 2500 but not 2400.

Which does he like?
900
1000
1100
1200

The sum of two numbers is 5 and their difference is 2003-06-16
From Akhil:
The sum of two numbers is 5 and their difference is 11. What is the product of the two numbers?
A 40% markup 2003-06-12
From Nick:
I am attempting to determine the Retail price of an item that costs me 11.00. Our company wants to sell it at a markup of 40%. I calculated this two ways, first the way I thought it should be done. Second, the way the calculator does it (and my accountant).

1. Cost + Cost*(percentmarkup/100)= retail price 11.00 + 11.00*.40 = retail price 11.00 + 4.40 = 15.40 retail price

2. Using the calculators Mark Up key the answer is 18.33. Or 7.33 more than the cost or 67%.

I am confused by this Mark Up key and how it calculates. I used a cost of \$10.00 and marked it up 50%. I thought it should equal \$15.00 but the calculator says \$20.00? This seems to be 100% markup, yes?

Can you explain the difference between the way I did it and the way a Business calculator does it?

From Joel:

I have this project to do about crosses and I can't think of what the answer is for the following questions: What is the area rule of the crosses (the table below will help you)?
Cross NumberArea sq cm
15
213
325
441
561

I also need to know what the formula is for it?

From A teacher:
I am going to be teaching second grade next year. How can I differentiate instruction in mathematics to meet the needs of all of my students, from those who need intervention to those who need challenges? What are some techniques I can try for this grade level?
Two trig problems 2003-06-10
From Bett:

I have this ongoing trouble with trig and solving triangles with laws of cosines and sines!! For example if it asks to solve triangle FGH, given angle G=102.7 , side f=14.2, and h=18.6. Now do I use law of cosines because I don't have the measure of an angle and length of the opposite side??I don't know where to go from here,I am totally confused!!!

I also have a problem with this word problem I have been doing. It asks: An airplane flies 847.5 km at a bearing of 237.3 degrees. How far south and west fo its original position is it? Huh? Please help!

How many gallons are in 83 liters? 2003-06-09
From Anita:
How many gallons are in 83 liters?
Definitions and descriptions 2003-06-08
From Tammy:
MY DAUGHTERS TEACHER ASKED HER TO GIVE BOTH A DESCRIPTION AND A DEFINITION OF THE FOLLOWING ... CIRCLE, SQUARE, TRIANGLE,HEXAGON...... THE LIST GOES ON. WHAT IS THE DIFFERENCE BETWEEN DEFINITION AND DESCRIPTION ? DO A CIRCLE FOR AN EXAMPLE PLEASE.
The metric and Imperial systems 2003-06-08
From Ashlee:
i am a year 8 student, and i am doing my Maths talent quest on the Metric and Imperial number system.

i was wondering, where did the 2 systems orginate and if possible, a little bit or information.

I also need to know the conversions of ounce, foot, mile..etc..from imperial to metric.

From Robert:
I have a radio controled car (scale size 1/43). This car can travel 490 ft. per minute. I would like to know how fast that is at that scale size in miles per hour (and Kilometers per hour)?
Spacing the spindles for a railing 2003-06-06
From Jennifer:

Scott is a homebuilder. He builds railings in which he places spindles. Spindles ar evertical posts taht are equally spaced beneath a horizontal bar. Scott would like a mathematical model to help him determine the amount of space to put between each spindle. The railing must follow the following criteria: The spaces between each spindle must be equal except for the ones at either end. Theses spaces are smaller. They are half the width of a spindle less than the other spaces. The number of spindles needs to be minimized since spindles are costly.

Help Scott determine what width of space to use between the spindles. Create a mathematical model to determine the width of space between each spindle in termso f the number of spindles. Use an 8' (96") railing that has 2 1/2" wide spindles. Explain your thinking. For safety reasons the maximum width of a space is 4"

Generalize you model to determine the width of spaces for total railing of length L and spindle width s

The square footage of a section of land 2003-06-04
From Diane:
We are trying to calculate the square footage of a section of land with the following dimensions:

One end is 100 feet. The other end is 105 feet.. One side is 350 feet and the other side is 372 feet. I calculated the area as 35,875 sq. feet, however, the brochure for the land says the area is 36,200 + sq. feet.

\$22,534.56 is what percent of \$27,820.00? 2003-06-04
From Minnie:
\$22,534.56 is what percent of \$27,820.00?
BEDMAS 2003-05-31
From Kristie:
(3x50)+20/5=?

I know bedmas but i forget how to do it.

\$1/week for week 1 and then double each week 2003-05-28
From A student:
I AM DOING A PROJECT FOR MATH I AM TRYING TO CREATE A SEQUENCE BASED ON: MAKING A SALARY OF \$1/WK FOR THE FIRST WEEK WITH IT DOUBLING EVERY WEEK FOR 52 WEEKS, SO MY SEQUENCE LOOKS LIKE THIS: 1,2,4,8,16,32,64,128,256,512,1024 ETC. THERE WOULD BE 52#'s TOTAL IN MY SEQUENCE.I BELIEVE IT IS CALLED A FINITE SEQUENCE. MY QUESTION IS HOW DO I CREATE A FORMULA/RULE FOR THIS PARTICULAR SEQUENCE? MY GOAL BEING TO FIND THE 52nd TERM IN THE SEQUENCE.
5 to the power n 2003-05-28
From Sam:
What is the integer n for which

5 to the n power + 5 to the n power + 5 to the n power + 5 to the n power + 5 to the n power = 5 to the 25th power?

Millimeters to inches 2003-05-28
From Brian:
I am a music instructor just trying to get a horn repaired. I have been trying to get replacement pearls for a keyboard of a horn. The mechanic needs the measurement in inches. The calibers say that the size is .115 mm can you tell me what that is in inches, I tried your formula of 2.54 mm per inch but this is a smaller size and I cannot seem to figure it out.
George and his goat herd 2003-05-27
From A student:

George the bulgarian goatherd drives his father's goats into a valley each morning and lets them browse there all day before driving them home in the evening.

he notices that each morning the goats immediately separate into groups and begin to feed the number and sizes of the initial groups vary some days there are nine and so days there are three or fewer. there can be groups of one or the whole group.

about every five minites one goat breaks away from each feeding group and these breakaway goats form into a new group.

George has noticed that by the afternoon, even though the goats continue their regrouping the sizes of the groups have stabilised, and there is always seven feeding groups.

How many goats are there in the herd? What are the sizes of the feeding groups once they have stabilised?

Two sequences that agree in the first 4 terms 2003-05-26
From A student:
Is it possible to have two formulas that define sequences that agree on the first four terms but not the rest?
The cross-section of a football field 2003-05-25
From Francis:
Have you ever walked on a football field covered with artificial turf? If so, you probably noticed that the field is not flat. The profile of the surface is arched and highest in the centre, permitting rainwater to drain away quickly.

height from base to highest point- 45.75 centimetres distance of the field- 50 metres

a) The diagram shows the profile of an actual field, viewed from the end of the field. Assuming that the cross-section is a parabola, find the algebraic model that describes this shape.

b) Use your equation to determine the distance from the sidelines where the field surface is 20 cm above the base line.

Two piles of cards 2003-05-24
From Sam:
A standard deck of 52 cards (26 red, 26 black) is separated into two piles, not necessarily equal in size. The first pile contains seven times as many black cards as red cards. The second pile contains a number of red cards that is a multiple of the number of black cards in that pile. How many red cards are in the first pile?
An array of pennies 2003-05-23
From Saundra:
If you have 100 pennies and you are suppose to make an array do you arrange the pennies by date?
The weight of a fish tank 2003-05-20
From A ponderer:
I had a question pertaining conversion units..I have a fish tank at home and the dimensions are 24, 44, and 48 inches, I want to find out how much it weighs in pounds when filled up with water...knowing water is 62.4 pounds per cubic feet...do I just divide the 62.4 pounds to 12 because I"m trying to find out through cubic inches.
The HCF and LCM of polynomials 2003-05-20
From Charanpal:

Question:
Find the HCF and LCM of the polynomials given below. Verify that he productof these HCF and LCM differs from the product of the polynomials, if at all, by a factor of -1

1. 1-x2 and x3 -1
2. 1 - x2 and x4 - 1

A trig identity 2003-05-20
From Patty:

1/ tanx + cotx = sinxcosx

R= 5.3lnx + x. 2003-05-11
From A student:
Reaction R to a dose x is given by: R= 5.3lnx + x. For a certain drug, R must not exceed 21. Show that a dose between 8 and 12 units satisfies this requirement & find, correct to 5 decimal places, the greates value of x which satisfies this condition?
Subtracting rational expressions 2003-05-10
From Simone:
hi, i'm totally lost. i understand that you need to find a lowest common denominator to subtract two fractions (rational expressions) with different denominators. but what if the denominators are "x-1" and "x". is x the common denominator? if so what happens to the "-1"? do you know of any live online help i can get with the following:

3/(x-1) - (1-2x)/x

x-6square root of x +8=0 2003-05-10
From Elizabeth:
x-6square root of x +8=0
Circumference 2003-05-09
From A parent:
Find the circumference use 3 1/7 for pi

1. r= 28 ft.
2. D=98 cm

Real numbers 2003-05-09
From Sirena:
what is a "real" number
sin theta = 7/8 2003-05-07
From Patty:
If sin0 = 7/8 and 0 is in quadrant 2, find the other five trigonometric functions of 0. (report your answers in radical form)
ABCD*4 = DCBA 2003-05-07
From Dee:

In the following problem, if the letters A, B, C and D represent some number, what numbers would they represent so that:

ABCD*4 = DCBA

2/sqrt(2) 2003-05-07
From Mike:
I was looking at an example of csc 45 deg where

csc = hyp / opp = 1 / (sqrt(2) / 2) = 2 / sqrt(2) = sqrt(2)

I just don't get this. If sqrt(2) = 1.4142145..... How can 2 / sqrt(2) = sqrt(2) as the example shows?

Rules of exponents 2003-05-05
From Carl:
Hi, I am a student who would like to recall how to multiply exponents. Here is such an equation:
6.02569 X 1025 X 5.254 =?

Such as 523 +15-12 =??

Write sin(3x) in terms of sin(x) 2003-05-05
From A student:
Write sin 2x in terms of sin x
Four digit palindromes 2003-05-05
From Heather:
How many palindromes were in between the numbers 1000 and 9999?
Integrating e^x sin(x) 2003-05-03
From Lech:
I am having trouble integrating the following expression by parts:

ex sin(x)

I used the integrator at http://www.integrals.com/ to find the solution,

? 1/2 ex cos(x) + 1/2 ex sin(x).

This is easy to confirm by differentiation, however I am confounded as how to arrive at the answer.

Answered by Penny Nom and Claude Tardif.
The volume of air flowing in windpipes 2003-05-02
From James:
The volume of air flowing in windpipes is given by V=kpR4, where k is a constant, p is the pressure difference at each end, R is the radius. The radius will decrease with increased pressure, according to the formula: Ro - R = cp, where Ro is the windpipe radius when p=0 & c is a positive constant. R is restricted such that:
0 < 0.5*Ro < R < Ro,
find the factor by which the radius of the windpipe contracts to give maximum flow?

positive multiples of 10 that are the sum of four consecutive integers 2003-05-01
From Taurus:
How many positive multiples of 10 that are less than 1000 are the sum of four consecutive integers?
A circle, tangent to two circles and a line 2003-04-30
From Keith:
I have a horizontal line (that is treated as a datum line or the X axis), with two circles having their center points at different heights from that line (X1,Y1 & X2,Y2). The two circles are also at different diameters (R1 & R2). Both circles and the line (X-Axis) do not intersect nor are they tangent. My goal is to determine the maximum diameter of an inscribed circle that will fit between all three.
Answered by Chris Fisher and Harley Weston.
A binomial probability 2003-04-30
From Erica:
In a biathlon, athletes shot at 20 targets. A particular athlete had a probability of 0.18 of missing a target. Assuming a binomial distribution, what is the probability, to the nearest thousandth, that the athlete hit exactly 16 targets?
Some shapes 2003-04-29
From Suzanne:
1. What shape has 12 edges all the same length?

2. What shape has 3 surfaces and 1 is curved?

Profit for a dance studio 2003-04-28
From Craig:
A dance studio charges \$80 per student for a series of 2 hour lessons. The studio's costs are \$30 per hour for the instructor, \$15 per lesson for the room rental, and \$3 per student for miscellaneous expenses. If x is the number of students enrolled in the class, express the studio's profit P(x) in terms of x. Find the profit if 10 students are enrolled in the class.
A skill testing question 2003-04-27
From Allan:
it is a contest Labatt Blue can you please give me the answer some people are saying 154 and some 34
Answered by Leeanne Boehm and Harley Weston.
20% of 40% of 500 2003-04-27
From A student:
What is 20% of 40% of 500
The product of four consecutive integers is 3024. 2003-04-25
From pillar:
The product of four consecutive integers is 3024. What are those numbers.
Gallons of rain 2003-04-25
From Jocelyn:
If you have a surface of 6500 square feet and 1 inch of rain falls on the surface, how many gallons of water does this equal?
38 minus 10 plus 12 divided by 4 times 16 2003-04-23
From James:
please help me work this math problem 38 minus 10 plus 12 divided by 4 times 16
Hidden by the curvature of the Earth 2003-04-23
From Shirley:
There are 2 six foot men. What would the distance be between them before one could not be seen because of the curvature of the earth?
Two intersecting graphs 2003-04-23
From Patty:

a) graph the equation

x2 - y - 4 = 0

x2 + y2 = 9
on the same set of coordinate axes.

I did not have a problem with this.

The problem is part (b) of the question ask: Find all solutions of the system in part (a) algebraically. Express answers in decimal form, accurate to two decimal places.

8 faces, 12 vertices, and 18 edges 2003-04-22
From Thomas:
I would like to know the proper name for this geometrical solid. It has 8 faces, 12 vertices, and 18 edges?
One one 2003-04-22
find the next two rows of numbers?
```     1
1 1
2 1
1 1 1 2
3 1 1 2
1 1 1 2 1 3
```

The effectiveness of a drug 2003-04-22
From A student:
A certain drug is found to be effective 80% of the time. Find the probability of successful treatment in two out of four cases.
Manipulating exponents 2003-04-21
From Denita:
Rewrite using only positive exponents:

(4a^4b^2)^4 * (4a^ -3 bc^2)^ -3

Chopping trees 2003-04-19
From Tamara:

The master needs some of the trees (twenty, to be exact) at the back of his spooky old mansion cleared to make way for a new evil laboratory, so he decides to send some his slaves to do the work for him.

He initially sends out four of his men, armed with axes, to chop the trees down. Due to the fact he is very impatient, every ten minutes he sends out another man to help with the work.

Assuming that it takes one man 30 minutes to chop down 1/3 of a tree, how long till all twenty trees are chopped down?

A tangent to a circle 2003-04-18
From Lech:
The line with equation y=mx is a tangent to the circle with equation x2+y2-6x-6y+17=0. Find the possible values of m.
Interest compounded daily 2003-04-18
From Bruce:
I recently received \$7,987.68. This amount consisted of \$7,543.61 invested at 6% per annum, compounded daily. I am trying to find out how many days this investment accrued interest.
The substitution method 2003-04-14
From Patty:

I need help with the following:

5x - 4y = 13

2y + 3x = -1

The square of my age was the same as the year 2003-04-14
From Pat:
Augustus de Morgan wrote in 1864, "At some point in my life, the square of my age was the same as the year." When was he born?
Area of a trapezoid 2003-04-13
My husband works with asphalt building roads. There are times when one end of the road will be (for example) 100ft wide the other end would be( for example) 200ft wide and he must figure the area in square feet. So far it has been a guessing game because he dosen't have the formula to figure the square feet.
Incremental standard deviation 2003-04-12
From Carlos:
I need to calculate the standard deviation for a group of data, but I don't know in advance what is the mean. Is there a way to adjust the STDV for each datum without keeping all of the previous values? This is needed basicaly for performance, so I won't need to read twice the same data (spend processing time) nor save the previous values (spend memory).
Answered by Andrei Volodin and Penny Nom.
A fractional inequality 2003-04-08
From Jessica:
Solve for x. Write in interval notation.

[(x2)-9]/[x-5] >= 0

The surface area of a cube 2003-04-07
From Sarah:
if the volume of a cube is 64 cm, then what's the total surface area? I also want to know how to show my work.
Jo's books 2003-04-07
From Miguel:
Jo announces, "I have more than 999 books."
Jean says: "No Jo! You have fewer than 1,000 books."
Mary says: "Jo has at least 1 book."
Only one of these statements is true. How many books does Jo own?

The area of a parallelogram 2003-04-06
From A student:
Find the area of the parallelogram with vertices (0,0),(7,2),(10,7),(3,5)
The height of an equilateral triangle 2003-04-06
From Rosa:
If Each side of an equilateral triangle is 10 m. What is the height?
How many hits? 2003-04-06
From Jack:

My name is Jack. I'm a uncle. Student is in the 5th grade email is above.

If a baseball player at sping training had a good season with the following:

one seventh of his hits were doubles.
12.5% of his hits were home runs.
But didn't have any triples.
How many hits did he have?

Can you give me an explanation of you solved the problem.

Divide a circle in 8 equal pieces 2003-04-04
From Naomi:
I have to divide a circle in 8 equal pieces but can only cut 3 times

Uses of conic sections 2003-04-01
From William:
My name is William and I am doing a research paper on conic sections for my 12th grade math class. Part of the project is to find two conic sections in our world today and explain what there purpose is. I really need help in this area because I've been searching the internet for where conic sections are used in our world today and I really can't find anything. If you can tell me specific building or a pyramid that contains conic sections that would be great. Or even something in the universe would be helpful.
Doubling the size of an object 2003-04-01
From Dave:
If I have a known surface area and volume of an unknown object and I want to double the size of the object, how do I find the new area and volume?
A handshake problem 2003-03-31
From Jaylan:
Suppose you and your partner attend a party with n other couples. Several handshakes took place. No one shook hands with himself (or herself) or with their partner, and no one shook hands with the same person more than once. After all the handshaking was completed, suppose you asked each person, including your partner, how many hands they had shaken. Each person gave a different answer.

Determine how many hands did you shake and how many hands did your partner shake when n=5

From A student:
Question:
i think i know the basics of how to solve direct quadratic equations,but how do i go about solving those word problems? i have tried them times and again, but nothing seems to work at all!they are driving me crazy! pls help!:):):):):)

1. bob & nick earned \$1260 each. bob's hourly wage is \$3 more than nick's hourly wage. he worked 2h less compared to nick. find the number of hours nick worked.
2. there are 2 tanks in henry's house. in tank A, the fish are all goldfish. they are bought at a total cost of \$259. in tank B, there are only guppies. the guppies were bought at a cost of \$1.20 each. a day later,henry bought 3 more goldfish and put them into tank A. the number of guppies in tank B is now twice the number of goldfish in tank A.the total cost of all the fish that henry has presently,i.e. goldfish & guppies, is \$355.30. given that the cost of each goldfish is the same,
a)find the initial number of goldfish in tank A
b)find the total cost of all the guppies.
3. a particular disc can be made to rotate at 2 different speeds. if it is made to rotate slower by 135 revolutions per hour, it wld require an additional 2.7 hour to make 315 revolutions. find the higher speed at which it can operate.

12*nC2 = n! 2003-03-30
From A tutor:
Solve for "N"

12*nC2=N!

The vertex of a cone 2003-03-27
From Holly:
I read your response to Callie about whether a cone has a vertex or not. Is it ONLY a vertex if both halves of the cone are together or can one half of the illustration have a vertex?
Can twice a square be a square? 2003-03-25
From Mike:
The other day it occurred to some students that they could think of no square number which is an integer, which can be divided into two equal square numbers which are intergers, Or put another way, no squared integer when doubled can equal another square integer. For example 5 squared plus 5 squared is 50, but 50 is not a square number.
Answered by Walter Whiteley and Claude Tardif.
A royal flush 2003-03-24
From Vikki:

A poker hand consists of 5 cards selected randomly from an ordinary deck of cards: find the probability of a ROYAL FLUSH : the 10 , jack, queen,king and ace of the same suit.

I was thinking somewhere along the lines of:

*the number of ways to get the suit is 4C1
*the number of ways to get a 10 out of the 13 cards etc....

Friends and enemies 2003-03-24
From Becky:

Consider a room that contains six people. Any two people are either friends of each other, or they are enemies.

A. Argue why there are three people, all who are friends, or there are at least three people, all who are enemies

B. Rephrase the situation using graph terminology, using all of these terms correctly: vertex, edge, graph, complement, clique, independent set, and bipartite.

A triangle and a circle 2003-03-21
From Jynks:
We need a formula that we can use to figure this out for work. We aren't math wiz's or students. Basically we know 3 points in space of a triangle, we know the length of each side and the length of the line from apex to base line. Each point of the base line ends upon the circumference of a circle. IS three a way to work out the radius of that circle.
Scientific notation 2003-03-20
From A student:
what is one millionth times one thousand in scientific notation.
Gallons in a tank 2003-03-20
From Leslie:
I am trying to figure the liquid gallons in a water tank that is 19" wide by 29.25" long and is 12.25" high. Could you tell me the formula to figure this out.
Harmonic numbers 2003-03-19
From Becky:
Harmonic numbers are Hn = 1 + ? + 1/3 + . . . + 1/n

Use induction to prove the following theorem:
For all natural numbers n, H1 + H2 + . . . + Hn = (1+n)Hn - n

A recurrence relation 2003-03-19
From Becky:
Solve this recurrence relation, with the initial conditions.

A1 = 10
A2 = 100
An = 10a n-1 + 29a n-2

The origin of integers 2003-03-19
From Travis:
What are the real life usages of integers? Also what is the origin of integers?
1 followed by a million zeros 2003-03-19
From David:
What do you call the number represented by the numeral '1' followed by one million zeros?
Two algebra problems 2003-03-18
From Kayla:
1st question- If a+b divided by a equals 6 and b+c divided by c equals 9, compute the numerical value of a divided by c. ( Your answer will be mumbers only, no variables.)

2nd question- Three adjacent faces of a box (a rectangular prism) have areas of 7, 14, and 18 square inches. Find the volume of the box. (Hint: Choose variables to represent the three sides of the box and then figure out the problem.)

Three proffs of a trig identity 2003-03-18
Prove the identity. cos [x + (y-pi/2)] = sin (x+y)

A hint was also provided which is: "Apply cos (alpha + beta) first then within that apply cose (alpha-beta)"

An equilateral triangle 2003-03-17
From Shirley:
An equilateral triangle is one in which all three sides are of equal length. If two vertices of an equilateral triangle are (0,4) and (0,0), find the third vertex. How many of these triangles are possible?
A sequence that converges to e 2003-03-16
From Dane:
Something I noticed fooling around with a calculator about 30 years ago.
Considering e = 2.718281828459045....
Using Window's Calculator you will find

1.111 = 2.8531167...
1.01101 = 2.731861...
1.0011001 = 2.71964085...
1.000110001 = 2.71841774...
1.00001100001 = 2.7182954...
1.00000110000011 = 2.178231875...
1.000000110000001 = 2.178219643...

There apears to be a pattern. My conjecture is:

1.'infinite number of zeros'11'infinite number of zeros'1 = e.

Runs 2003-03-16
From Diana:
How many arrangements are there with n 0's and m 1's, with k runs of 0's? (A run is a consecutive set [1 or more] of the same digit; eg. 000 111 0 11 00 has three runs.)
Distributing r identical balls into n distinct boxes 2003-03-16
From Diana:
How many ways to distribute r identical balls into n distinct boxes with exactly m boxes empty?
Working backwards 2003-03-14
From Melody:
Triva went to the ardcade at the state fair to win some goldfish. She already had some goldfish at home, but wanted more. She won enough goldfish to double her stock. Her mom made her give four away. She put her new ones in the tank with the others, by the morning half of the goldfish had died. Triva's friend gave her six more. The next morning two-thirds of her goldfish died. She was left with two goldfish after giving one to a friend. How many goldfish did she start with?
1575 2003-03-13
From Sharyn:
find 6 integers that when multiplied with each other equal +1575 and when the same integers are added together equal zero. there are more positives than negatives and one of the numbers is a double digit between 10 and 20
An arc of a circle 2003-03-12
From Melissa:
A strip of wood is 16 ft. long and is bent in the arc of a circle. Two radii, from the center of the circle to the ends of the arc, form a right angle. What is the approximate distance from one end of the wooden arc to the other?
Harmonic numbers 2003-03-12
From Becky:
What can you tell me about the limit of harmonic numbers as it reaches infinity?
Monomials 2003-03-11
From Roxy:
Explain why (x+y)z is not equal to xz+yz? P.S. Z is an exponent
Surface area of a sphere 2003-03-11
From Kim:
a sphere has a surface area of 128 pi sq. units. What is its exact radius?
formula is 4 pi r2 I believe but how do I get radius

Division names 2003-03-10
From A parent:
what is the answer to a division problem called
Three digit number 2003-03-10
From Grace:
What three digit positive integer is exactly 32 times the sum of its digits?
A question on combinations 2003-03-06
From Jose:

I'm an architect student and have a question on combinations. I have a grid of 3 x 3, hence a total of 9 spaces. I have 3 elements to place in this grid.

How many possible ways are there of arranging this elements on this grid ? (order, orientation not important)

First putting the elements each in its own space and secondly allowing the elements at a given moment to "share" one space.

Since I got kind of obsessed with this I went ahead and graphically did all the combinations allowing "sharing", a grand total of 729. How could I have known this before hand ?

Answered by Penny Nom and Claude Tardif.
Mary typed a six digit number 2003-03-06
From Pillar:
Mary typed a six digit number, but the two 1's did not show. What appeared instead was 2002. How many different six-digit numbers could she have typed?
(n+17)(n+7) = 0 2003-03-05
From Janea:

What is the answer to 1. (n+17)(n+7)=0

What is the answer to:2. (y-15)(y-100)=0

Can a square be a rhombus? 2003-03-04
From Beth:
Can a square be a rhombus? Some sources say yes, some say no. Some sources define a rhombus as a quadrilateral and parallelogram with equal sides, but without right angles. Some sources say a square is a special case of a rhombus. Clarity, please!
y < 2x + 1 2003-03-01
From Erika:
how can I solve and graph y<2x+1 and which side in the graph should i shade after i finish solving my inequality?
Finding the area when the perimeter is known 2003-02-28
From Yvette:
What is the size of an area in sqare feet when the perimeter totals 842 feet.
Sides are 190ft+180ft+200ft+54ft+118ft+100ft.

______cm=0.048km 2003-02-27
From Antonette:
______cm=0.048km
Can a square be considered a rectangle? 2003-02-27
From Carla:

Can a square be considered a rectangle? (since opposite sides are same length and parallel)

Would a regular hexagon or octagon be considered a parallelogram since its opposite sides are parallel? or does a parallelogram HAVE to have only 4 sides?

A number line 2003-02-27
From Shery:

My seventh grader problem of the month

0__________1______________5____>

This is a arrow, the number should be below

A.Mrs Decker created an arrow representing a number line shown above. She wanted to find points and label them with a heart (G) for Valentine's Day so that the fraction 5/g is less than 1. (be sure to mark the G and not the fraction 5/g). She pondered, "Are there any other locations for G?" Is so help her description the location of all these points. If not why not?

A regular polygon 2003-02-26
From Melissa:
The measure of each interior angle of a regular polygon is eight times that of an exterior angle of the polygon. How many sides does the polygon have?
X times Y equals ten million 2003-02-26
From Baneen:
Would you be able to tell me which two numbers would compute ten million without any number having zeros in it?
(xy)z = 64 2003-02-26
From Melissa:
How many ordered triples of positive intergers (xyz) satisfy (x[raised to the y])raised to the z = 64?
A section of land 2003-02-25
From Bev:
How many acres in a section of land? How many square miles is in a secion of land?
The length of an arc 2003-02-24
From Gavin:
does anyone have a formula for calculating the length of an arc if I have the circle radius and the cord length of the arc??
Excluded values 2003-02-22
From Josh:
Why do you think it is necessary to include the "excluded values" when you write your answers to rational expressions?
A trig identity 2003-02-22
From Ron:
We have spent hours trying to solve the following identity without success. Can you give us some hints as to how it is done?

1 + tan(x) tan(2x) = tan(2x) cot(x) -1

The number of possible outcomes with 8 games 2003-02-21
From Gianni:
If 8 basketball games being played(no ties), which means a total of 16 teams, what are the total number of possible outcomes that can occur.
Percentage change in completion rate 2003-02-21
From Remo:
In the year 2000 300 out of a possible 600 completed a phone survey for a total of 50% completion rate.

In the year 2001 20 out of 100 possible people completed the survey when it was re-done. This is a completion rate of 20%

To figure out the percentage change between the years can just use the difference between the percentage figures I already have? Or can I calculate it the same as you would for non-percentage numbers. For example you gave an example here of a salary increase from \$20 to \$95 being an increase of 375%.

Would I solve my problem the same way expect substituting my percentages (.5 and .2) in place of \$20 and \$95?

Deduct 60% from \$150.00 2003-02-21
From Mike:
How do you get this answer?
deduct 60% from \$150.00

Percentage decrease 2003-02-20
From Hope:
What number decreased by 331/3% is 30?
Density 2003-02-19
From Rob:
What is the formula for converting cubic feet to pounds? (with any substance)
Hundreds, thousands, millions,... 2003-02-19
From Karissa and Jasmeen:
hundreds, thousands, millions, - can you help us with the rest of this sequence - we are trying to find the largest number
Sasha's candies 2003-02-18
From Pat:
Tick-tac-toe

Sasha and Trudy are playing tick-tac-toe. Sasha agrees to give trudy two pieces of candy for each game Sasha loses, and Trudy agrees to give Sasha three pieces of candy for each game that Trudy loses. After playing thirty games, Sasha has the amount of candy that he started with. If no ties occurred, how many games did Sasha win?

Order of operations 2003-02-16
From A student:
How is the order of operation used in everyday life other than in a math class or at school? Also .... Can you give me a list of all the mathematician that are still living that uses the order of operation?
Numbers in base 5 2003-02-16
From Lori:
I'm trying to help my 6th grader with converting numbers like 82 to base 5 and 182 to base 12. We saw your examples on 613, but still are confused.
Order of operations 2003-02-15
From Debbie:
Question: 20-(9+4)x7=?

A determinant 2003-02-13
From A student:

I have to find the determinant of the following matrix

 -2 3 1 2 4 -3 0 -2 5 1 4 2 1 -3 5 2 3 4 -1 2 6 0 3 2 -4

Wrap a rope around the equator 2003-02-12
From Ali:
If you take a rope and wrap it around the equator and then overlap it 6ft. and cut off the extra then you loosen it up so the ends meet how far would it stand off the ground?
Multiples of all four of the numbers 2, 3, 4, and 5 2003-02-11
From Stephanie:
How many of the first 1000 positive integers are multiples of all four of the numbers 2, 3, 4, and 5?
Storyteller figurines 2003-02-10
From A student:
It takes 3/4 of an hour to bake a storyteller figurine. If only one figurine can be baked at a time, how many can be baked in 6 hours?
Splitting weight 2003-02-10
From Jin Ho:
A balance scale has only two weights, 1 ounce and 4 ounces. In only three weighings split 180 ounces of seed in two bags of 40 and 140 ounces.
Finite differences 2003-02-10
From Jenny:

I need to find a formula that will work with any number.
I am finding the volume of a 3d cross- shape. Here are my results so far:

```Term Number      0   1    2    3     4      5
nth term         1    7   25   63   129    231
1rst diff           6   18   38   66     102
2nd diff              12    20   28   36
3rd diff                  8     8    8
```

I can't seem to find a formula that will work with any number. Any help would be much appreciated.

Three consecutive positive intergers 2003-02-09
From Yew:
Prove that when we multiply any consecutive positive intergers, the result is always divisible by 6.

ex. (7)(8)(9) = 504 = 6 (84)

AABBBCCCCAABBBCCCC... 2003-02-09
From Patty:
The pattern AABBBCCCCAABBBCCCC continuously repeats. What is the 2003rd letter in the pattern? Please help, I am trying to figure out.
Millilitres and millimeters 2003-02-09
From Iwan:
I was just wondering whether a millilitre was equal to a millimetre, if not, what is there difference.
BEDMAS 2003-02-09
From Stefanie:
I do remember the rules of BEDMAS, but for some reason this question puzzles me.

6 X 9 - 3 + 44

I started with the Multiplication

54 - 3 + 44

But then I got stuck, do I proceed with adding the 44 and subtracting the 3
or figure out what -3 + 44 is, but then how would that work with 54?

Two investments 2003-02-07
From A student:
you have \$7200 in principal and invest different sums @ 10% and 14%. You receive 920 at end of term. (one year)What amounts are invested at what rate?
The area of an isoceles triangle 2003-02-07
From A student:
I have to find the area of an isoceles triangle with one angle side of 30 degrees, and length of base 5. Could you please help me solve this problem?
A 15% markup 2003-02-07
From Holly:
what is 15% markup of 58.89? please show equation and why? which is correct? 58.89 divided by .85 or 58.89 times 1.15
Two equations in two unknowns 2003-02-06
From Patrick:
What are all ordered pairs of real numbers (x, y) for which: yx2 - 7x + 12 = 1 and x + y = 6?
Transformations of pattern blocks 2003-02-06
From Cheryl:
I am trying to help my 8th grade son with Transformations - use of patttern blocks. He has to trace a figure and reflect it across the x-axis, which I can do, but then it indicates include ordered pairs - that confuses me.
Two airplanes leave Dallas 2003-02-06
From A student:
TWO AIRPLANES LEAVE DALLAS AT THE SAME TIME AND FLY IN OPPOSITE DIRECTIONS. ONE AIRPLANE TRAVELS 80 MILES PER HOUR FASTER THAN THE OTHER. AFTER THREE HOURS, THEY ARE 2940 MILES APART. WHAT IS THE RATE OF EACH AIRPLANE?
The sum of the first 1000 even integers 2003-02-06
From Jill:
What is the sum of the first 1000 even integers?
Milliliters 2003-02-04
From James:
What is a milliliter?
Factoring 2003-02-04
From Marcin:
I am having a really hard time with the factor theorem. Can you please help me with the following? (a'3 means a to the exponent 3)

a)8a'3+64b'3c'6
b)8x'4-12x'3-44x'2+24x
c)x'4-21x'2-100

Filling in the back yard with dirt 2003-02-04
From Joe:

We just bought a house and need to start filling in the back yard with dirt to level it out.

I measure 37'x 56' by 2' deep on an angle.

I will be building a retaining wall at the 2' deep portion. The slop will go from the 2' to nothing at the top or near the house. I can't remember how to get the Sq. foot or cubic yards.

A train with 2 cars 2003-02-04
From Michael:
A train with 2 cars is traveling at a speed of 80 km/hr from town X to town y, located 800 km from each other. At the same moment that the train departed, a passenger started to walk back and forth from one end of car B to the other at a speed of 100cm/sec. Arriving in town Y, the passenger had already gone and returned 720 times. The length of car A is that of car B plus one fourth of the length of the locomotive, and the length of the locomotive equals the length of Car A plus one fifth of the length of car B. What is the total length of the train?
Problem solving 2003-02-03
From Brigitte:
My daughter is having lot's of problem with problem solving she is in grade 6. she is using mathematics in action from macmillan/ mcgraw- hill. Do you know of any way she can get help, and if there is any tests on line
Arithmitic sequence 2003-02-01
From A student:
I am having problems solving this arithmetic sequence... 1, 5, 10, ___, 50, 1.00, ___, 10.00, ... I believe the answers to be 25 and 5.00 but I can't figure why.
Combinations of 1,2,3,4,5 and 6 2003-02-01
From Kyle:
Today I was aked a question by my geometry teacher. It was, what is the sum of all the possible combinations of the numbers 1, 2, 3, 4, 5, and 6. He said all the possible combinations were 720. I would like to know how u could do this, and what the answer is.
1+2+3+...+500 2003-01-31
From Brian:
What is the sum of the numbers from 1 to 500 inclusive?
Triangle perimeter 2003-01-30
From An Aunt:

Hi I'm the aunt of a middle school child. He need help with two problems and I don't understand how to show he how to do them. Can you help me.

1. How do you find the perimeter for X=4, X=0.7, and X=5/6?

2. And an acute triangle that bottom is (3X+1) cm, left side is (X+4) cm and the right is (2X+5)cm.

Can you show me not only the answer but also the steps that you used.

I have three circles... 2003-01-30
From Tony:
I HAVE THREE CIRCLE THAT IS CIRCLE TOGETHER: IN CIRCLE A, THE NUMBERS ARE: 11 I KNOW IS IN CIRCLE A, BUT I HAVE THE: 5 THAT IN A AND C, I HAVE THE 2 IN THE CIRCLE C AND B AND AND A, THE CIRCLE C I KNOW THAT 10 IS IN THE CIRCLE THE 4 IN CIRCLE A: AND B: IN CIRCLE B, I KNOW NUMBER 13 IS IN CIRCLE B; BUT I HAVE THE 3 IN CIRCLE B AND C AND I HAVE THE 2 IN CIRCLE B AND C AND A ,THE 4 IN CIRCLE B AND A.
HOW DO I FIND THE SUM IN CIRCLE C AND IN B IN BOTH CIRCLE A AND B AND B AND C NOT IN CIRCLE B, AND NOT CIRCLE C.

Fibonacci exam 2003-01-28
From Mike:

My son will be participating in the national math contest. He is a grade 4 student but will be writing the Fibonacci exam for grade 5. He has been given last years exam for practice. Parents have been ask to assist for this part. I was therfore hoping for a little "inside" help on several questions with answers & short explanations. This with a would be greatly appreciated.(from last years exam)

1. With 3 weights, Mathusalem can weigh any object that has a weight which is smaller or equal to 13 kg, but that weighs a whole number of kilograms. He wants to weigh an object of 7 kilograms. To do so, he must place two of the weights on the left side of the scale, and the third one on the right side. Which one will he have to place on the right side

a)4 b)3 c)6 d)2 e)5
2. Mathilda uses a rectangular prisms to build stairs. The cross section of each prism is a square which has a side of 1 dm. Mathilda has already put in place 4 steps of a staircase that must have a height of 10 dm. When finished, the staircase will have a volume of 550 dm3. What will the width of the staicase in dm be?

a)10 b)55 c)11 d)1 e)100
3. The year 1991 was the last palindrome year of the second millennium. The year 2002 is the first palindrome year of the third millennium. Including 2002, how many palindrome years will there be, altogether, in the third millennium ?
a)8 b)2 c)10 d)182 e) 9

Greatly appreciated,
Mike

Factoring a trinomial 2003-01-26
From A student:
how do you factor: Xsquared + 8x + 12
Extraneous solutions 2003-01-24
From Paul:

What is an extraneous solution and in what cases do you get one?

How do you know it is extraneous?

From Sabrina:

[What is the greatest common factor of 20,28, and 36?] next problem is

[5k+7(k+8)= ] next problem

[Curtis simplified 0.8 divided by 0.2 x 0.04 and got 10. Latoya Simplified and got 1.6. is either correct? Can you explaine how you got the answer please.]

Dorothy and the wizard 2003-01-24
From Ken:

dorothy was going to see the wizard of oz...she stopped at the bakery and bought a box of cookies.

she met the scarecrow and gave him half the cookies. she ate half of the remaining cookies and threw one half cookie away.

she met the tin man and gave him half the cookies. she ate half the remaining cookies and threw one half cookie away.

she met the lion. she gave him half of her cookies. she ate half the remaining cookies and threw the LAST half cookie away.

how many cookies did dorothy leave the bakery with?

6 digit numbers from 0,0,2,2,4,4 2003-01-23
From Amanda:
How many 6 digit numbers can you make from the numbers 0,0,2,2,4,4, giving that 0 cannot come first. The number has to contain 2 twos, 2 fours, and 2 zeros.
Answered by Penny Nom and Claude Tardif.
The cousin of Sally's sister's boyfriend 2003-01-23
From Michael:
Sally went to a farm to buy eggs. Returning home, she gave half of them to her sister who, in turn, gave a third of those she had gotten to her boyfriend. The latter, after eating one third of the eggs that he had gotten, gave the rest to his cousin. Given that each egg weighs 70 grams, that Sally cannot carry more than 2.5kg, and that the eggs were raw, calculate how many eggs the cousin of Sally's sister's boyfriend received.
The area of a regular n-gon 2003-01-22
From Sophie:

We have been given a piece of maths coursework. A farmer has exactly 1000 metres of fencing and wants to fence off a plot of level land. she does not mind what the shape is but it must have a perimeter of 1000m. She wants to fence off the plot of land which contains the maximum area. Investigate the shape, or shapes that could be used to fence in the maximum area using exactly 1000 metres of fencing each time.

I have investigated many shapes, and I feel that a circle will have the biggest area. However we have also been asked to investigate shapes with 20 and 30 sides. My dad said that there is a formula for finding out any area of land. Do you know of this formula, if so I would be very grateful if you were to email it to me.

Rational expressions 2003-01-22
From A student:

// = the main fraction line

1.) a+1/a-1 + a-1/a+1 // a+1/a-1 - a-1/a+1

2.) 2/a(squared)-3a+2 + 2/a(squared)-a-2 // 2/a(squared)-1 + 2/ a(squared)+4a+3

The least common denominator 2003-01-21
From Brittan:
Hi there I need help! My name is Brittany and i am in the 6th grade.

I need help finding the least common denominator(LCD), and the book says Find the LCM of the denominators and i've done that and then it says write equivalent fractions,using the LCM as the least commonn denominator.The directions say Use the LCD to write each pair as like fractions. and the problem is 1/8 and 5/40. Could u explain how in the word u do this? Thanks a lot

Brittany

A penny, a nickel, a dime, a quarter, and a loonie 2003-01-21
From Blaine:
I have 5 coins: a penny, a nickel, a dime, a quarter, and a loonie. How many different amounts of money could I pay using any combination of these coins?
Jo's books 2003-01-21
From debra:
Jo announces: I have no more than 999 books.
Jean says: No Jo, You have fewer than 1,000 books.
Mary says: Jo has at least 1 book.

Only one of these statements is true, How many books does Jo own?

I do not know HOW to approach this problem and solve it.

From Dan:
Why are equations of the form aX2 + bX + c =0 call quadratic? The quad indicates 4 but the power is 2.
Cutting a board 2003-01-20
From George:
A person has a sheet of board which he saws into two (2) pieces. The length of the first piece is two thirds the length of the original board, while the length of the second piece is four feet longer than the first piece. How long was the original board? (the length is defined as the longer of the two sides of the board)
Division by zero 2003-01-19
From David:
I've been to your site and am interested on the subject of division by 0. It's easy enough to give answers, but it's very hard, especially in this case, to make someone understand a mathematical problem.

It's been about a year since my Calc class, and we never went over division by 0, only infinite numbers and such. My question is: How would you work a problem of (real number) / 0 ? As ignorant as it may sound to you, I am having trouble grasping this since I've only begun to understand some of it. Perhaps you could help.

25% more 2003-01-16
From Charlie:
If I buy something for \$10 and want to sell for 25% more, do I multiply by 1.25 or divide by .75? Or another way - why do I get \$13.33 when dividing by .75 ?
From Erikson:
I am a student in the 10th grade and attending advanced math at my high school. I was assign to do a report about the unit circle and the radian. But there seems to be no information available about the history of the radian; who first found out about them, which civilizations used it if any. Well, hopefully you'll assist me in this troubling question. Thank you for your kind consideration.
0.027 acres 2003-01-16
From Cory Lee:
How many square feet are in How many square feet are in .027 acres??
NO RED-HATTED DWARVES ALLOWED 2003-01-14
From Dulce:

There are 1000 dwarves in Dwarfland. Now as you know, dwarves are born with either red or white hats on.

The dwarves in Dwarfland love to party. Every night, they all flock to the same club to dance the night away.

One day, a sign is posted at the club: "NO RED-HATTED DWARVES ALLOWED". A certain number of days pass, after which all of the white-hatted dwarves are in attendance,and none of the reds.

How did the red hats know not to come?

Assumptions:

1. The number of red and white-hatted dwarves need not be equal. There are at least 1 of each color.

2. There are no reflections or mirrors in Dwarfland (i.e. the dwarves can't see the color of their own hat), and no dwarf can reveal through direct or indirect means the color of another dwarf's hat.

3. There is NO COMMUNICATION among dwarves

4. No white-hatted dwarf ever misses a night of partying

Collinear Points 2003-01-13
From Gary:

Which of the 4 points are collinear when you construct the following concurrent lines or rays of a triangle?

1. P(1), the point where the angle bisectors intersect.
2. P(2), the point where the altitudes (or extensions) intersect (inside or outside of the triangle).
3. P(3), the point where the medians intersect.
4. P(4), the point where the perpendicular bisectors (or extensions) of the three sides of a triangle intersect.

This is for my 9-12 high school class in geometry.
My name is Gary

Gary

Answered by Harley Weston and Chris Fisher.
Would it be worth paying \$20K for 4 chances... 2003-01-13
From Steve:

If I've got 4 chances to to achieve X goal, and in each chance that I have I've got a 65% chance of achieving this goal, what is my overall probablity of achieving this goal? Also, what would it be after each of my 4 chances (i.e., for my 2nd chance, would it be (.65 * (.65*.65)? I've forgotten some basic probablity theories, and would appreciate any help on this.

With the probablities above, would it be worth paying \$20K for 4 chances to achieve the goal or \$8.5K for only 1 chance to acheive the goal? (at 65% probability)

5x(-2)-32/8 2003-01-13
From A student:
I'm having problems solving this question:
5x(-2)-32/8

What is larger than infinity? 2003-01-12
From Dana:
What is larger than infinity?
Answered by Claude Tardif and Harley Weston.
Cubic yards in a gravel pile 2003-01-10
From Ron:
I am looking to find a way to measure gravel piles to get yards. They are generaly not square.it would be like pouring sand out of a bag into a pile. they generaly are concave in dimension. can you help. I have attached a picture to show a small scale what I am working on is in much larger volume.
A rectangular prism 2003-01-09
From Julie:
How many faces on a rectangular prism and how many bases? Can the base also be a face and can a face also be a base?
Intercepts 2003-01-08
From Nay:
my name is nay 8th grade student how do i figure out an intercep and does it always have to have (0, ) or ( ,0)?
Repeating decimals 2003-01-08
From A student:
If k=.9repeating, and 10k=9.9repeating then 10k-k=9k, k=1 therefore .9repeating=1 and 1/3=.3repeating 3x1/3=.3repeatingx3, 3/3=.9repeating, therefore 1=.9repeating

It would seem to me that .9repeating approaches one but never quite makes it. Can you clarify?

The area of my lot 2003-01-07
From Linda:
I have a lot that is 210 feet in the front, 240 feet in the back and the sides each measure 150 feet. How many square feet is this all together and how close to an acre is it?
Integration of 1/(2+cos(x)) 2003-01-07
From A student:
integral from pi to 0 of

dx/(2+cos x)

i used the substitution t=tan(x/2) and i ended up with

integral from +infinity to 0 of

2dt/(t2+3)

which looks like an inverse tan function , and i ended up with sqr(27)/2 pi , which is not the same as my calculator's answer , so i suspct i am doing some thing wrong. can some one tell me where i am going wrong please.

Mean and median 2003-01-04
From Jan:

I have a question re: mean and median. I know what the difference is but just need some clarification on when you would use the mean and when you would use the median. Isn't it the case that with a skewed distribution the average (mean) would be higher or lower than the median, but with a normal distribution they would be very similar values?

If you have any examples to help explain this that would be greatly appreciated.

I am a teacher (of sorts!) and the person who is asking me the question is actually my boss!

Constructions of polygons 2003-01-03
From Garrett:
Our teacher just finished the constructions unit, and he mentioned briefly about odd sided figures such as pentagons and septagons, only that they're very hard. My question is, how do you draw, with a compass and a straight edge, a pentagon and septagon?
Two numbers have a ratio of 5:3 2003-01-01
From Patricia:
Two numbers have a ratio of 5:3. The larger number is 36 more than half the difference of the two numbers. What are the two numbers?
Augmented matrix 2002-12-31
From Michelle:
I am trying to augment a matrix so that i can find the values of the variables a, b, and c. For the life of me i can't find a solution to the matrix: 3 -5 2 ' 22 2 3 -1 ' -9 4 3 3 ' 1 I thank you for your help, Michelle
Successive coefficients in Pascal's Triangle 2002-12-27
From Quincy:
There is a formula connecting any (k+1) successive coefficients in the nth row of the Pascal Triangle with a coefficient in the (n+k)th row. Find this formula
Answered by Penny Nom and Walter Whiteley.
Averages of Averages 2002-12-21
From Amy:
If in the month of October the % of Payments Received was 80.74% and in November it decreased to 69.36%. Can you take the 80.74-69.36/69.36 to get the % of difference. In otherwords can you take the % of difference when the numbers you are comparing are %'s????

Can you also take an average of an average? For example, average number of payments received in October was 25.00%, average number of payments received November was 50.00%, and the average number of payments received in December was 15.00%. Do you average (25.00%, 50.00% and 15.00%) or do you have to go back to the numbers that calculated the averages. For example, October 25.00% was based on 25 payments being received out of a possible 100. So instead of taking the average of the averages, do you take the average payments and the average customers over the 3 months and calculate the average???

20% of 40% of 500 2002-12-19
From Richard:
What is 20% of 40% of 500?
The intersection of conics 2002-12-19
From Glenda:
We are studying systems of equations where two conic sections are the two equations that we are solving simultaneously. We were studying the number of solutions that are possible if you have an ellipse and a parabola. We all agree that there can be none, one, two, three or four solutions. The question that the students had for me was whether or not a portion of an ellipse and a parabola can overlap and thereby allow an infinite number of solutions. What should I tell them?
Answered by Chris Fisher and Harley Weston.
The units digit of 2 to the power of 31921 2002-12-18
From A student:
If 2 to the power of 31921 is multiplied out, what will be the units digit?
Odd and even 2002-12-17
From Martin:
I am a graduate engineer trying to teach single digit addition to my 8 year old grand-daughter. My questions follow.

Assume a child does not know what multiplication and division are.

Assume the child knows how to count from 0 to 10

How do you explain that 2, 4, 6, 8 and 10 are even numbers

And 1, 3, 5, 7 and 9 are odd numbers

And these three facts?

3. when you add an even number and an odd number, the answer is odd?

Can all of these be reasoned out, without using the concepts of multiplication or division?

Calculations 2002-12-15
From Mahdi:
This problem is rather general, but it usually makes a lot of problems. I almost have no difficulty in math and physics questions, but unfortunately I'm not at all accurate in simple one or two digit calculation. I even sometimes make silly mistakes in simple sums like 7+4=12 or 4+5=11! Is there any effective way to reduce these mistakes?
A bouncing ball 2002-12-14
From Eman:

Q : When a childís ball is dropped from a height h metres on to a hard, flat floor, it rebounds to a height of 3/5h metres. The ball is dropped initially from a height of 1.2m.

1. Find the maximum height to which the ball rises after two bounces.
2. Find the total distance that the ball has traveled when it hits the floor for the tenth time.
3. Assuming that the ball continues to bounce in the same way indefinitely, find the total distance that the ball travels.

Two modes 2002-12-12
From ali:
I have a math assignment to pick the mode in a set of data. 12 and 21 both appear twice in the data set. What is the mode?
Units 2002-12-12
From Debbie:
The general equation for a parabola is y = ax 2 + bx + c, where a, b, c are constants. What are the units of each constant if y and x are in meters?
Construct a pentagon 2002-12-12
From Mary:
We were wondering what the instructions/formula, step-by-step, is to make a pentagon.
Answered by Chris Fisher and Penny Nom.
A sphere with a hole - cylindrical shells 2002-12-11
From Kathy:
Suppose you make napkin rings by drilling holes with different diameters through two wooden balls (which also have different diameters.) You discover that both napkin rings have the same height, h.
1. Guess which ring has more wood in it and why.
2. Check you guess: Use cylindrical shells to compute the volume of a napkin ring created by drilling a hole with radius r through the center of a sphere of radius R and express the answer in terms of h.

Factoring 2002-12-11
From Larry:
Question:

how do u factor trinonmials

EX: X 3 + Y 3

X 3 - 8Y 3

8X 2 - 72

64A 3 - 125B 6

Find a, b and c 2002-12-10
From Sameer:
Question:

a+b+c=180
b=a+(120/2-5)
c=b-(130-10)/6
a=?
b=?
c=?

Fractions 2002-12-10
From Jean:
What are some activities to use with advanced students in grade 7 to apply their knowledge of fractions and decimals. I'm looking for a project type of activity.
From Katie:
just bugging the hell outta me and I cannot figure it out for the life of me.

1)x-2x-1 =0
Find both roots. You must simplify both of your roots. This equation requires the use of the Quadratic Formula. I have tried everything for this and I am still either getting the wrong answers, and end up getting really frustrated. If you could find the answers and tell me how you did it I would greatly appreciate it! Then the second problem is

2) The square of a certain negative number is equal to 70 decreased by 3 times the number. Find the answer! On this one I set it up but still came out with the wrong answer. So if you could help me on this one I would greatly appreciate it!

y = 1 - sin(x + 60) 2002-12-10
From Eman:
Sketch the graph of y = 1 - sin(x+60). for 0 <= x<= 360, giving the coordinates of the maximum and minimum points and the pints where the curves crosses the y axis.
ALL of the possible 3 digit combinations of 0 - 9 2002-12-09
From Melissa:
I need to find out ALL of the possible 3 digit combinations of 0 - 9. Eg: 000,001,002,003. This is going to take me VERY LONG time. Any suggestions.
How many billions equal one trillion? 2002-12-07
From Ryan and Aylah:
How many billions equal one trillion?

A function that is onto but not one-to-one where f:N-->N 2002-12-06
From Lisa:
A function that is onto but not one-to-one where f:N-->N
Integer arithmetic 2002-12-05
From A student:

I am just learning about integers. Can you show me in a way I might understand....My teacher can tell me what is required to do the math, but it just doesn't make sence to me.

(+4) - (-3) =+7

Why is the answer not +1

A rope trick 2002-12-05
From Jerry:
My name is Jerry and I am a math teacher at the secondary school level in the greater Toronto area. I posed the following problem to my enriched grade 10 math class that I found in the book called "Mathematics and the Imagination" by William Kastner. According to the author, it is posible for two people linked to each other with two ropes around their hands, to separate themselves without letting go of the rope. The students had lots of fun trying to accomplish this problem using skipping ropes from the Phys Ed department, but with no success.
Factoring a cubic 2002-12-05
From Dorota:
I got a problem with factorise the expression
2x3+11x2-5x-50.

Which is the better buy? 2002-12-04
From Lynda:
my question is the big can held 18 ouces and cost \$2.52.The small can held only 12 ounces and cost \$1.08. Find both unit prices. which can was better buy?
65,125 2002-12-04
From Brittany:
I am a three-digit number.When you reverse my digits,a larger number is formed.the product of me and the new number is 65,125.What number am I.
Answered by Chris Fisher and Claude Tardif.
The dimensions of a box 2002-12-03
From Paula:
My son, who is in secondary school, needs to make a box with the inside dimensions of 1.25 cubic feet. It's supposed to be more in the shape of a rectangle than a square.

I would like to know the equation to use to find the inside dimensions of a box if I know how many cubic feet (or inches) I need the inside to be.

A Normal probability problem 2002-12-03
From A student:
The height of married men is approximately normal with mean 70 and standard deviation 3. The height of married women is approximately normal with mean 65 and standard deviation 2.5. What is the probability that a random married woman is taller than a random married man?
A geometric sequence 2002-12-02
From Wanda:
the fifth term of a geometric sequence is 5/16. the common ratio is 1/2. What are the first four terms of the sequence.
Tiffany plays first board for her middle school chess team 2002-12-02
From Patty:
Tiffany plays first board for her middle school chess team. Since she joined the team last year, she has won 27 of 51 tournament games. That's a winning percentage of about 53%.

If Tiffany went on a winning streak, how many games would she need to win in a row to raise her winning percentage to 60% Use variables and equations to communicate the method you've used to solve the problem.

How do you estimate the equation of a parabola? 2002-12-01
From Audrey:
How do you estimate the equation of a parabola? I have a project where a must find parabolas in magazines and then estimate their equation.
Trigonometry 2002-12-01
From Lance:
My question is:

FIND ALL SOLUTIONS cosx=1-sin(x/2) if x[0,2pi)

ALSO:

Given cscx=-5/4 and cot>0, find csc(x/2) and cot(x/2)

Trigonometry problems 2002-12-01
From Chiara:
1. Find tan 35pi/4
2. Graph y = cos2x - 2sinx

The height of a triangle 2002-11-29
From Dean:
Could you please tell me the formular for me to calculate the height of a triangle. I have the angles and side lengths. I am trying to calculate the height of an isosceles triangle, does this make a difference from a normal triangle or is the formular the same.
Constructing a tangent to two circles 2002-11-28
From Tom:
I have two circles, different sizes a known distance from each other. We know the radii of the circles. How do I construct a line that is tangent to both circles relative to the segment that connects the centers of both circles?
Answered by Chris Fisher and Penny Nom.
x + y=80 and x + z=100 2002-11-28
From PJ:
x + y=80
x + z=100

can you solve for x, y or z?

Miles per hour 2002-11-28
From Liz:
If a car has traveled 16 miles in 30 minutes, how many miles per hour did they go?
The length of an arc 2002-11-27
From Nancy:
If all I have is the length between 2 ends of an arc (72"), how do I find the length of the arc at its apex and the radius?
Combinations of 1,2,3,...,10 2002-11-27
From Gord:
If I had the numbers from 1-10 how many different combinations would i have.....would it be 100....since that is 10 squared.
[x*(x+2)] + 1 = (x+1)(x+1) 2002-11-27
From Melissa:
While teaching the multiplication table to my daughter I noticed an interesting pattern. It goes something like ...Take a whole number
...multiply the two numbers together
...add one to the resulting number
...it will now be equal to the original number plus one, squared.

Making 7 2002-11-26
From Bill:
At one time I had the answer to this math equation but I have lost it and can't seem to regain it. I may be going at it wrong but as I recall there were the numbers 1 through 4, and the std operators, +, -, /, *, and parentheses. The object was to make the four numbers with the operators equal to 7. Each number and operator may be used only once. My 9 year old loves these quizzes but I can't give it to her if I can't provide the correct answer.
A two stage rocket 2002-11-26
From Hoda:
a two stage rocket accelerates in free space by ejecting fuel at a constant relative speed , v(ex). the full fuel load makes up 80% of the initial mass of the entire two stage rocket . the rocket accelerates from rest until at the end of the first stage when 75% of its fuel has been burnt. find an expression for the speed of the rocket at the end of the first stage in terms of v(ex).
A lampshade from a cone 2002-11-26
From Ellsie:
I need to make a pattern to cover an old lampshade. This is actually the bottom portion of a cone. Please help me figure out how to draw this pattern, so that we can complete our project.
Decimals in everyday life 2002-11-24
From Fritz:
How do you use decimals in your every day life?
Factor completely 2002-11-21
From Shelley:
these two questions are to be factored completely but i have no idea how to factor them
1. (x-4y) 2 - 3(x-4y) - 4
2. x 6 + y 6

Filling A swimming pool 2002-11-21
From Sarah:
A swimming pool is being filled by three pumps. Alone pump A would take 6 hours, pump B would take 3 hours, and pump C would take 3 hours. If all three pumps are used to fill the pool, what fraction of the process is pump A.
The volume of a juice jug 2002-11-21
From Edward:
I try to find the measurement for a juice jug. I have the height of the jug and need the jug to hold 2.5 Liter of juice. Can you help me out with the formula.
Performance reviews 2002-11-21
From Lara:
Perhaps you can help.

He's doing performance reviews at work.

The average performance review is 3.92 on a 5.0 scale. This person would receive a 3.5% raise for next year.

The highest performance review is 4.9 and this person would recieve a 6.0% raise for next year.

How do I solve for the other performance review numbers.

What percent is the same as three eighths? 2002-11-21
From Katelin:
What is the percent of three eight's?
Composites, primes, factors and common factors 2002-11-20
From Connie:
My son can't remember what a composite number is, what a prime number is and the explaination of factors and common factors. Help!
Differentiating inverses 2002-11-20
From Amy:
f(x)= x3+x+1, a=1 find g'(a) (g = f -1). I am having trouble finding g(a).
4 x abcd = dcba 2002-11-20
From A student:
Say you have a four digit number (e.g. abcd) and you multiply the number by 4. The answer you get will be the reverse order of the number you started with (dcba). What is the number? The four digits (a,b,c,d) cannot be the same number or cannot be repeated.
Answered by Penny Nom and Claude Tardif.
abc,abc 2002-11-20
From Pam:
Prove or disprove that "every number of the form abc,abc (where a, b, and c represent digits) is divisible by 7,11, and 13"
Round to hundredths 2002-11-19
From Brittany:
Can u tell me how to do a problem like this:

35 divded by 4.8= Round to hundreths.

Why is 5 divided by 1/7 greater than 5 divided by 2/3? 2002-11-19
From Elizabeth:
1. Without performing the division, explain why 5 divided by 1/7 is a number greater than 5 divided by 2/3.
2. Is the least common multiple of two prime numbers always their product? Why or why not?

Answered by Diane Hanson and Penny Nom.
The horse race 2002-11-19
From Pat:
The Horse Race Three horses run a race. In how many different ways can the three horses finish the race if ties are allowed?
A cubic 2002-11-18
From Jessica:
"For what values of the constant p does f have 3 distinct real roots?" The function is f(x)= x3 - 6x2 + p, where p is an arbitrary constant.
Answered by Claude Tardif and Penny Nom.
Gears and ratios 2002-11-17
From Matt:
if gear A has 12teeth and Gear B has 16teeth and gear C has 10teeth and gear A turns 40 times how many times will gear C turn
The 24 game 2002-11-16
From Michael:
Hello, my name is Michael and I am in elementary school .. We have a game we play in math class called 24 game. In it each card has 4 numbers on it. Each number can only be used once, in any order, using multiplication, subtraction, division, or addition. We are stuck on one and wondered if you could help. The four numbers are 10-9-16-4. And they must equal 24. Any clues?
A 40% markup? 2002-11-15
From Amy:
Please help? I own a basket and bouquet company, I have two retail stores with a markup of 40% on the price of the items I sale to them. I do not understand their conversion chart and I hope you can help me.

A bouquet that I sale for \$12.50 wholesale to the retail is marked up at a rate of 1.675 or (40%). I do not understand how the calculation of 1.675 is arrived at ... how is this 40%. I was told to multiply my wholesale price of \$12.50 X 1.675 and I would arrive at the markup price of 40% the retailer would sale the item for.

The product of two consecutive numbers is 41 more than their sum 2002-11-15
From A mother:
THE PRODUCT OF TWO CONSECUTIVE NUMBERS IS 41 MORE THAN THE SUM OF THE NUMBERS. WHAT ARE THE NUMBERS?
The substitution method 2002-11-15
From A student:
Solve by using the substitution method.

x = 3y - 1
x + 2y = 9

A pattern in a table 2002-11-14
From Thamar:
how do you solve for pattern in a table like

 the top row is the bottom row is 2 6 12 17 z 9 13 19 24 blank

question ask in each blank space write a rule to find the next number in the table

Algebra 2002-11-13
From Carol:
I am a confused parent trying to help my dau hgter solve some math problems and I need help.

3[x-4]=27

For what divisors can you get a remainder of 8? 2002-11-13
From David:
When dividing a 3-digit number by a 1-digit number, for what divisors can you get a remainder of 8?
The volume of water in a hose 2002-11-13
From David:
I trying to find out how much water 500 ft of 3/4 inch hose will hold. I'd also like to know how you figured the answer.
Subdividing a circle 2002-11-11
From David:
Say you have a cirlcle.

Then you draw 2 dots on the circle.

Then you connect the dots with lines.

The circle is divided into 2 parts.

If you do the same with 3 dots and connect each dot to each dot with a line then you get a circle with 4 parts.

4 dots with lines connecting all (6 lines) = 8 parts....

Fuel consumption 2002-11-11
From Guy:
When a car is driven 'normally' the feul consumption is 7.5 per litres per 100km. On a particular journey the car was driven in 'hard' and the consumption changed to 9.1 litres per 100km. Fuel cost 80p per litre. Calculate:

a) The extra feul consumed.
b) The extra cost of feul, in pounds, for the journey when the car was driven in 'hard'.

From A student:

ex. 7sqrt(2) + sqrt(50) - 2sqrt(18)

10sqrt(3/5) - 24sqrt(5/3)

3sqrt(2/9) + 1/2sqrt(32) + sqrt(9/8)

x intercepts 2002-11-10
From Laura:
Find the x intercepts for the graph of the equation.

x 2 - x - 12 = 0

(93+n)+158=93+(28+158) 2002-11-10
From Parents:
(93+n)+158=93+(28+158)
A bus is 60% occupied 2002-11-09
From Joe:
A bus with a seating capacity of 60 people is 60% occupied. At the next stop one-third of the people get off the bus and 3 people get on the bus. The bus is now ___% occupied.
Three bags of marbles 2002-11-08
From A student:
I have 3 bags of marbles

1 bag is labeled blue; 2nd bag is labeled red; 3rd bag is labeled blue & red

all the bags are mismarked

your job is to take one marble from 1 bag look at it and correctly label all the bags

Prime numbers 2002-11-08
From Lonna:
Is 2 a prime number or not??
Why is 1 not considered a prime number?

Two tanks of water 2002-11-08
From A student:
A 2000 L tank containing 550 L of water is being filled with water at the rate of 75 L per minute from a full 1600 L tank. How long will it be before the two tanks have the same amount of water?
Cubic centimeters 2002-11-07
From Rita:
Was in emergency room yesterday-MD aspirated 40cc of fluid from my knee--what does a "cc" equate to?
G = 3H - 5 2002-11-07
From Kash:
G=3H-5, for H solve for the given variable
The identity property 2002-11-07
From Stephanie:
I am a student teacher this semester in the third grade. I was looking at our math competencies and saw that we needed to teach the identity property. Is this the same as the distributive property? If not, what is it?
Chisanbop 2002-11-07
From Paul:
I'm trying to find the book/books that explain this system? I have one small book that explains the very beginning of the system, but covers only about 10 to 20%. I'v tried several book sellers and have had no luck.
Substitution 2002-11-06
From John Paul:
I took a math test last week, and there was a problem which the teacher checked as incorrect. It was:

Solve: (a)RcTc=360;(b)RmTm=480;(c)Rm=2Rc; (d)Tm+Tc=15

I solved the problem and I got the following values for each variable.

For Rc=40 For Tc=9
For Rm=96 For Tm=5

I don't see nothing wrong, but the teacher checked it as wrong. Could it be a checking mistake?

Determining a parabola 2002-11-06
From Shelley:
let (0,3) and (1,9)and (-1,1) be given points in a parablola. Determine a b and c
What is nth term? 2002-11-06
From Joga:
What is nth term:

First sequence:
2, 4,7,11, 16, nth term

Second sequence:
4,10, 28, 82, nth term

18m-11+ -7 2002-11-06
From Sophia:
what is 18m-11+ -7 (m = to 12)?
A house's selling price 2002-11-05
From Tanisha:
a CERTAIN REAL-ESTATE AGENT RECEIVES \$6 FOR EVERY \$100 OF A HOUSE'S SELLING PRICE. HOW MUCH WAS A HOUSE SOLD FOR IF THE AGENT \$10,725._
Compass points 2002-11-05
From Mhairi:
I was asked this in maths but I am not sure if it is geography. Name all the compass points? We have been given 8 but he told us there is more and we have to name them.
The percentage grade of that hill 2002-11-05
From Cathy:
If there is an 80ft climb over a kilometer(about 3280ft) what is the percentage grade of that hill?
An octagon of perimeter 1,000 meters 2002-11-05
From Stephen:
my son has to work out the area of a octagon with a outside perimeter of 1,000 metres,
Clown has eight steps to climb 2002-11-05
From A mom:
I'm a parent of a grade two student. What is the best way to help my son figure out a math comprehension problem?

Clown has eight steps to climb, is shown in a picture with front foot on third step and behind foot on first step. Each time he climbs three steps, he falls back two. How many times did he have to climb up to reach the top.

Should I get him to do a line graph or math equations. On his own he came up with the answer seven. I think the answer is six. I did 0+3=3, 3-2=1, 1+3=4 and so on, In think my why is alittle confusing to him. Is there a simplier why to explain it to him.

A twelve-volume set of encyclopedias 2002-11-04
From Ron:
A novice librarian shelved a twelve-volume set of encyclopedias in the following order from left to right. Volumes 8, 11, 5, 4, 9, 1, 7, 6, 10, 3, 12, and 2. Using her system, where will volume 13 go?
Rounding 27.27 2002-11-03
From A parent:
If you have a problem 27.27 and you need to round to the first 7 the answer would be 27

Would 27.0 be acceptable as well or is it completely wrong.

Mathematics and Music 2002-11-01
From Hannah:
I am looking for a science fair project to compare math and music and how they relate. If you have any project ideas for me, they would be greatly appreciated.
How would you find the length of the chord? 2002-10-31
From A draftsperson:
If given the length of an arc and the distance from the midpoint of the arc to the midpoint of a chord, how would you find the length of the chord and the radius of the arc. The chords endpoints are the same as the the arcs endpoints.
A coin is tossed 11 times 2002-10-31
From A student:
There are 2 people that are playing a game in which a coin is tossed 11 times. The first player gets a point for a toss of heads. The 2nd player gets a point for a toss of tails. whoever gets 6 points wins. Suppose that so far the first player has 2 points and the second player has 4 points. What is the probability that the first player wins the game?
Answered by Andrei Volodin and Penny Nom.
Mrs. Klein has been losing 1 pound a week for the last year 2002-10-30
From Brett:
On her diet, Mrs. Klein has been losing 1 pound a week for the last year. Her husband weighs 110 pounds more than she does now. If his weight is twice what her weight was 6 weeks ago, how much does mrs. Klein weigh now?
An isosceles triangle 2002-10-30
From Stan:
What two different base lengths can an isosceles triangle have with sides on both remaining at 13 inches? How do I show this?
Answered by Paul Betts and Peny Nom.
A triangular prism 2002-10-30
From Daniel:
I was wondering what a triangular prism was.
How many empty seats are there? 2002-10-29
From Ronnie:
Three new students arrived in class. Teacher says there are 210 ways you can set. How many empty seats are there in the classroom? After new student are assigned seats, how many empty seats will remain?
Variance 2002-10-29
I am trying to solve a standard deviation question, I have 30 data points to use, should I group the data before solving for variance or should I just use the raw data.
Simplifying Variable Expressions 2002-10-28
From Erika:
i would like to ask you a mathematical question on Simplifying Variable Expressions. The question is 2(n-4)+3.
Jimmy's hits 2002-10-27
From Patty:
One seventh of Jimmy's hits were doubles
12.5% of his hits were homeruns
He did not have any triples

How many hits did Jimmy have? (Be sure to include the equation that represents the number of hits)

10 hours before 7:15 2002-10-27
From Jessica:
It is evening 7:15. What time would it be 10 hours earlier?
An identity? 2002-10-27
From Jenna:
I can't prove
```
1-sinQ     1 ---- = tanQ + --- 1+sinQ      cosQ
```

The four colour theorem 2002-10-27
From Rhonda:
is there an actual equation for the four colour map theorem??? i cannot find it anywhere!! if so can you give a breif description on how it works!!
x 4 + x 5 = 100 2002-10-27
From Bill:
One of my students has stumped me. He asked how to solve the equation 4 x + 5 x = 100

All I can think of are graphing methods to get an approximate solution. What am I missing?

What are the digits? 2002-10-24
From Ebenezer:
There are three digits. The middle digit is zero and the sum of the first and last digits are is 13. When the number is reversed it is increased by 297. What are the digits?
From Richard:
I'm using a grading program for the first time this year. (ok, that's not a question) I require my students to record their grades in a Scorekeeper when they get them back. I'd like to know if my students can keep up with averaging their grades just as the grading programs automatically averages them when I put them in the spreadsheet.
Answered by Penny Nom and Claude Tardif.
How many trees were planted in March? 2002-10-20
From Allison:
The number of trees planted by the Alpine Nursery in April was 3 more than twice the number of trees planted in March. If 71 trees were planted in april, write and solve an equation to find how many trees were planted in March.
Is a square a rectangle? 2002-10-20
From Nona:
Are squares rectangles? Third grade math teacher told a student this was true. Grandmother needs confirmation on this!
Answered by Claude Tardif and Harley Weston.
At the zoo 2002-10-20
From A student:
The number of adults at the zoo was 2/9 the number of children. there are 700 more children than adults. The number of men was four times the number of women. The number of girls was four times the number of boys. Find the total nymber of men and boys at the zoo.
Simplify 2002-10-19
From A student:
well i need to simplify this problems out and i cant do it so here is one
` 3x^2+6x-45 ------------ = 3x^2+21x+30 `

Exponential notation 2002-10-19
From Ivy:
I understand how to figure out for example 4 to the power of 3,what I don't understand is how to figure it out using both negative numbers and negative exponents,as an exaple -4 to the power of 6 and what makes this different that (-5) to the power of 7,please help me if you can.I am an adult taking correspondence and finding it quite frustrating.
Is it a prime? 2002-10-19
From JV:
6x to the third power plus 5x plus 15, is that prime or not prime, and whichever it is, how can you prove it? ya dig?
Use each digit 1-9 only one time each,... 2002-10-19
From Megan:
Use each digit 1-9 only one time each, divide the numbers into 3 groups, make one 2 digit number, one 3 digit number, and one 4 digit number. There are 6 combinations of these numbers in which you can multiply the 2 digit and 3 digit number together to get the 4 digit number (using each digit 1-9 one time each). What are they!!!!!!!!!????????????
An identity in trigonometry 2002-10-17
From Alex:
I really need help with proving this identity. (1+cosx+sinx)/(1+cosx-sinx) = secx + tanx
The orthocentre 2002-10-17
From Elsie:
1. Find the orthocentre of the triangle with vertices at A(-3,4), B(10, -3) and C(3,-2).

2. Find the distance of point X(3,8) from the line that passes through Y(-2, -2) and Z (3, -2).

The repetition of doing many straight forward problems 2002-10-16
From Dan:
I am the father of a very bright 9 year old girl. She is very interested in math and she grasps concepts very quickly. I am concerned that she may become bored with the repetition of doing many straight forward problems. Her current math teacher has her working in a challenging math book and she is doing 3+ digit multiplication. She misses 2 or 3 out of ten of these problems due to simple addition errors. Should she continue to practice these problems until she can get them all correct? Or, should she move on?
Answered by Kathy Nolan and Claude Tardif.
Integers in real life 2002-10-15
From Rica:
What are the real life usages of integers?
A sale price 2002-10-15
From Chester:
A jacket is on sale for 32% off. Find the original if the sale price is \$89.00
From Micheal:
When I am driving down the road and see a sign that says for example steep grade ahead 6% grade etc etc what does this mean?
Two problems 2002-10-14
From Seçkin:
i am from turkey i am a teacher in a collage i have two difficult question which i havent solve yet these are very important for me....
A functional equation 2002-10-14
From Rob:
Let f be a function whose domain is a set of all positive integers and whose range is a subset of the set of all positive integers with these conditions: a) f(n+1)>f(n)

b) f(f(n))=3(n)

Two problems 2002-10-14
From Eva:

a) How many different equivalence relations can be defined on the set X={a,b,c,d}?

b)Show that 6 divides the product of any 3 consecutive integers. I know it is true that 6 divides the product of any 3 consecutive integers. However, i have problem showing the proof.

Answered by Leeanne Boehm and Penny Nom.
Pythagoras in three dimensions 2002-10-14
From Miki:
A room is 6m long, 5m wide and 3 m high. Find the distance from the corner of the floor to the opposite corner of the celing.
Three algebra problems 2002-10-13
From Veronica:
Solve the following inequality:

5(xsqured-4)/(xto the 5th(2x-5)to the 3rd) < or equal 0

Solve the following equations for all roots

square root of x+2=-1+square root of 2x+3

what's ZERO FACTOR PROPERTY???

The hypotenuse of an isosceles right triangle is 7cm. long. Determine the lenghts of the other sides.

Tree diagrams 2002-10-12
From Denean:
1. For lunch, students can choose juice or milk; hamburger or pizza; and a banana or apple. How many lunch combinations can the students make?

2. In an experiment, Monty can use paper towels or cloth. He can choose red, green, or yellow food coloring. How many combinations are there?

Statistics 2002-10-11
From Ed:
Suppose 25 percent of all U.S. workers belong to a labor union. What is the probability that in a random sample of 100 U.S. workers, at least 20 percent will belong to a labor union?
Kilometers to miles 2002-10-09
From A student:
how many miles are in 16 kilometers?
From Lisa:
The longest-lived US presidents are John Adams(age90), Herbert Hoover (also90), and Harry Truman (88). Behind them are James Madison, Thomas Jefferson, and Richard Nixon. The lattter three men lived a total of 249 years, and their ages at the time of death form consecutive odd integers. For how long did Nixon, Jefferson, and Madison live?
8 squares from 12 sticks 2002-10-08
From A student:
If you have 12 sticks the same size, how do you make them into 8 squares?
From Debbie:
The school newspaper is interviewing 6th grade students to see what sports they follow regularly on TV. Of the 70 students interviewed; 40 enjoyed basketball; 40 enjoyed baseball; 40 enjoyed football; 20 enjoyed basketball and football; 22 enjoyed baseball and basketball; 27 enjoyed football and baseball; and 12 enjoyed all three sports. How many students out of the 70 interviewed didn't follow any one of the three sports?
Answered by Leeanne Boehm, Penny Nom and Walter Whiteley.
From Michael:
I would like to know, how to solve this Complex number: quadratic equation. ix 2 + x -i = 0
Relatively prime 2002-10-04
From Natasha:
I really need help with this middle level math question. My little brother is asking me and I have no clue what the answer is. Explain what it means when two numbers are negatively prime. (?)
Answered by Kathy Nolan and Penny Nom.
\$100 is split between four guys. 2002-10-03
From Stephan:
\$100 is split between four guys. A,B, C, and D. How much money does if person get if B has four more dollars than A, C has 8 more dollars than B, and D has twice as much money as C?
Rational expressions 2002-10-03
From Ashley:
1/x(squared) + 5/xy
Exponent 0 2002-10-02
From Debbi:
can you please tell me what the exponent 0 is (i.e. 70)
The interrelations of the propositions in Euclid I 2002-10-01
From Rob:
I'm a student at St. John's College in Santa Fe New Mexico, are school is devoted to the great books and we're now reading Euclid's Elements in english and Attic Greek. We have an assignment to show a frequency or flow chart of how all the propositions of book one are interrelated.
Two rate problems 2002-09-30
From Rebecca:
1. There are two small holes in the bottom of a tub filled with water. If opened, one hole will empty the tub in three hours; the other will empty it in six hours. If both holes are opened at the same time, how long will it take to empty the tub?

2. An airplane flies 400 miles per hour in calm air. It can cover 900 miles flying with the wind in the same time that it can cover 700 miles against the wind. What is the speed of the wind?

A geometry problem 2002-09-29
From Sonia:
Given AB||CD; m a. Find the measures of
b. Is there enough information for you to conclude that

0.99999... 2002-09-26
From Erica:
Yesterday in my 8th grade math class we were being taught how to convert a Repeating Decimal into a fraction. Since I, for some odd reason, seem to understand math better than the rest of my classmates, i began to drown out my teachers explaination for the rule. While she was about half way through with explaining mixed decimals i came up with an unsolvable question. Like I said before, I understand how to turn a repeating decimal into a fraction, but how would I turn a repeating .9 into a fraction? We all know it would equal 9/9, but doesn't 9 over 9 also equal 1? Even though it comes very close to one, it never really equals one. I'm very confused about this and i would love it if you could clear this up for me.
Proof by induction 2002-09-26
From Pooh:
Use induction to show that

1 2 + 2 2 + .....+n 2 = (n 3)/3 + (n 2)/2 + n/6

Painting a car 2002-09-24
From A student:
Dan can paint a car in 4 hours. Luke can pain the same car in 6 hours. Working together, how long would it take them to pain the same car?
Number play 2002-09-24
From Julie:
Organize these numbers and the operations so that each equation is correct. Use each coice only once per equation.

36 18 12 6 - + ( ) /

_________________________ = 22

_________________________ = 41

Dividing fractions 2002-09-23
From Angie:
When I was taught to divide a fraction, I was told to multiply the reciprocal. Many times I find I can just divide the fraction, and it saves all the simplifying after.

For example, 4/6 x 9/14 divided by 2/4

I would say 4x9divided by 2=18 over 6x14divided by 4 =21, so the answer is 18/21 but if I multiply the reciprocal, I would end up with 4x9x4 over 6x14x2 which equals 144/168.

So, why are we taught to do it this way? Is it necessary?

A cone that is cut off at the top 2002-09-23
From Stuart:
I have to work out the dimensions and arcs of a cone that is cut off at the top.

I.e Top diameter is 33mm to bottom diameter is 43mm and the depth is 80mm

Are you able to work what the flat of this cone would be as I need to design within the flat area and then have it cut out.

I really need to know what the flat of it is before it is cut and curled to form the above cone.

Solving an equation 2002-09-22
From Emanuel:
how do u solve these problems?:

30/x=7+ 18/2x

3m+1/4 = 2- 3-2m/3

Ceiling 2002-09-22
From Joe:
Does the ceiling of a number mean the ceiling of 1.3 is 2 and
the ceiling of 1.5 is 2 and
the ceiling of 1.8 is 2.

Or the ceiling of 1.3 is 1.5?

A max/min problem 2002-09-21
From Evelina:
A window is the shape of a rectangle with an equilateral triangle on top. The perimeter of the window is 300 cm. Find the width that will let the maximum light to enter.
Fractional exponents 2002-09-20
From Jill:
The problem is with fractional exponants:
10 1/3 mult. by 10,000 The 1/3 is an exponant of 10.

The entire earths' population would fit in the state of Texas 2002-09-18
From Roz:
I have been told that the entire earths' population would fit in the state of Texas and each person would have 1/2 acre. Is this true.
How long will it be before you reach your friend? 2002-09-16
From Margaret:
Your friend runs at 8 miles per hour and you drive at 40 miles per hour, hence the diatance between you is decreasing at 32 miles per hour. You firend left 2 hours before you so how far has he gone in that 2 hours? How long will it take for the distance between you to decrease to 0 miles if the distance is decreasing at 32 miles per hour?
A Circle is evenly divided into six equal triangles 2002-09-16
From Marilynn:
A Circle is evenly divided into six equal triangles leaving an area between the outside of the circle and the one side of the triangle. This area is measured as 3.14. What is the length of the radius, one line on the triangle?
A million sheets of 30 cm long paper 2002-09-15
From Jennifer:
if you put a million sheets of 30 cm long paper end to end, how many kilometer long would the paper be from begining to end?
Formulating equtions 2002-09-14
From Theresa:
Hello. In math class we have to formulate equations for certin questions for extra credit. We are allowed to ask anyone and anyone can do it for us and explain it to us. Could you please do that? Here are the questions
1. Jordan has 3 times as much money as Reva. Together they have \$44. How much money does each have?

2. The Tigers played 48 games. They won twice as many as they lost. How many did they win?

3. There are 900 students in Sewickley Academy. There are 20 more girls than boys. How many girls are there?

4. A board 400 cm long is cut into 2 pieces. One piece is 66 cm longer than the other. Find the lenght of the shorter piece.

Sums of evens 2002-09-14
From Rosa:
How do I find a geometric way to easily compute sums of consecutive even numbers 2 + 4 + 6 + ....
Answered by Leeanne Boehm and Harley Weston.
Mixing solutions 2002-09-13
From Margaret:
In a chemistry laboratory the concentration of one solution is 10% hydrocholoric acid (HCl) and that of a second soulution is 60% HCl. How many mL of each should be mixed to obtain 50 mL of a 30% HCl solution??
Base 5 numbers 2002-09-13
From Vera:
? how do you change a base 10 number to base 5
How many dominoes? 2002-09-13
From A student:
Dominoes are split into two halves. If you were allowed up to 6 dots on each half, how many options of dominoes could you get?
The number of decimal places in 1 over a power of 2 2002-09-12
From Allan:
Does anyone notice that the maximum number of decimal place of the number 2 dividing 1 and its increment (4, 8, 16...etc) is the same as the power of number 2? eg. 22=4, thus the max number of decimal of 1/4=0.25 which is 2 decimal place and 2 is the number of power of 2 take 64 as example: 26=64, and take 1/64=0.015625 which has 6 decimal place (and is the power 6)

Is there such a law in math? If yes, can you tell me what it is? Or is this my discovery?

Use a 4 four times 2002-09-12
From Amanda:
The question is what is if you can only use a 4 four times and get the answer 12, 10, and 6
7+8+9+...+1000 2002-09-11
From Shirley:
My question is what is the formula for adding up numbers when you don't start with number 1? For example 3 + 4 + 5 + 6 = 18. But how could you arrive at the answer without adding all the numbers?
From Kathleen:

i have problems like

3x2 - 4x - 11 = 0 how do i work out that problem? i have the formula written down but it doesnt seem to register for me.

The sum of the first one hundred even numbers 2002-09-10
From Arthur:
What is the sum of the first one hundred even numbers?
A fish weighs 10 pounds more than half its weight. 2002-09-10
From Rebecca:
A fish weighs 10 pounds more than half its weight. How much does it weigh?
The factor theorem 2002-09-10
From Yael:
Prove (x - a - b) is a factor of x3 - a3 - b3 - 3ab (a + b)
How do start from 2700 and get 35% back out? 2002-09-09
From Dennis:
2000 x 0.35 = 700 + 2000 = 2700
How do start from 2700 and get 35% back out? If I have 2700, how do I figure out that 35% of 2000 is 700 and adding the two them together will get me 2700?

A linear function 2002-09-09
If y = 9x - 13 does it represent a linear function? And if it does what is its slope and is it a direct variation?
The community garden 2002-09-08
From Michele:
Bryce, Duanne, Juliana and Sonya share a 40ft by 48 ft rectangular portion of the community garden in the neighborhood. With this space each has their own rectangular garden plot.

-Bryce is the only one with a square plot. its are is 1/2 the area of Duanne's -The area of Bryce's plot is 2/3 the area of Julianna's plot. Their plots have one side in common.

-Sonya's garden has an area twice that of Julianna's garden.

What are the dimensions of each person's garden plot?

Algebra 2002-09-08
From Heather:
This question is from an 8th grade Algebra classs. I am a parent asking for help to explain to my child. Q: d=25t2.
Mean, median and mode 2002-09-08
From Ramona:
1. How do you calculate the mean, median, and mode?

2. what are each of their definitions?

Weighing pumpkins 2002-09-08
From Jennifer:
Suppose five pumpkins are weighed two at a time in all possible ways. The weights in pounds are recorded as 16, 18, 19, 20, 21, 22, 23, 24, 26, and 27. How much does each individual pumpkin weigh. NO FRACTIONS!
The area of a triangle 2002-09-07
From Phill:
How do you find the area of a equilateral and other triangles?
Sanding a wooden block 2002-09-07
From Wanda:
If a wooden block, 2in height, 3in width, and 6in length is sanded and 1/8 of an inch is removed from the top and from the bottom, how much is the volume of the block decreased?
Subsets of the Real Number System 2002-09-07
From Christine:
In looking for a French equivalent of the word "integer", I found that the word seems not to actually exist in French, and that Canadian schools use the term "natural number" to describe what we have been trained to call "whole numbers," while using the term "whole number" to describe what we have been trained to call "integers."
Social security numbers 2002-09-06
From Chris:
How many different number combinations are there for the social security system? We know that there are only a certain ammount of combinations available and the current US population is at 281 million. The number system should include as many nine digit combinations as possible using the numbers 0-9 in multiple different spots.
I am a 3 digit number. 2002-09-06
From Jasmine:
I am a 3 digit number. My last digit is 3 times my first digit. My firat digit is twice my middle digit. What numbers am I? There are at least 2 correct answers?
8,27,64 . . . 2002-09-05
From Mike:
We have been trying with no luck all night to complete the following math pattern (next 3 entries) 8,27,64 . . . Any ideas??
What really is pi? 2002-09-05
From Rachel:
what really is pi? 3.1444
Dan is 4 inches taller than Mike. 2002-09-04
From A parent:
Dan is 4 inches taller than Mike. Together they are 8 feet 8 inches tall. How tall is each boy in feet and inches.
1/8 in decimal form 2002-09-04
From A student:
explain how you put 1/8 in a decimal form
Intercepts 2002-09-04
From Tamara:
Why is it that the x intercept the value of y is 0 and at the y intercept the value of x is 0?
1, 2, 4, 8, 16, 32, etc. 2002-09-04
From Ginger:
I've been working with finding the nth term for a few weeks, and i can't seem to figure this one out!

1, 2, 4, 8, 16, 32, etc.

Monthly rent 2002-09-04
From Al:
How do you figure monthly rent if the charge is 11.00 per sq. ft. and there are 1,000 sq. feet?
A limit 2002-09-03
From Circe:

Lim 3x 3+ax+a+3 /(x 2+x-2), X->-2

Addends can be grouped differently but the sum does not change 2002-09-03
From Jodia:
I have been searching the web for over an hour & a half now for the answer to the following question:

The _____ states that addends can be grouped differently but the sum does not change.

A schedule for a fantasy football league 2002-09-01
From Steve:
i am in a ten(10) team league, split evenly into two five team divisions. we play a thirteen(13) game schedule and would like to play each team in your own division twice, and each team in the other division once. according to my rudimentary mathematics that equals 13 games. a good schedule should look somthing like this: team 1-5 = division 1 team 6-10 = division 2 team 1 should play teams 2-5 twice and teams 6-10 once.
A group of 9 2002-08-31
From William:
what is the mathmatical name for a group of nine like a group of 3 is called 'triplets'
Proof by induction 2002-08-31
From Tabius:
Use mathematical induction to prove that the following formulae are true for all positive integers:

a) 1 + 3 + 5+...+(2n - 1) = n 2

b) 2 n > n.

How many cubic feet are in a cubic mile? 2002-08-30
From William:
How many cubic feet are in a cubic mile?
A square of tiles 2002-08-30
From Rosa:
How do I go about finding a formula for the number of tiles I would need to add to an arbitrary square to get to the next sized square?
38-10+12divided by4multiplied by 16 2002-08-30
From Brenda:
my math question is as follows: 38-10+12divided by4multiplied by 16=?
< and > 2002-08-30
From Kelsey:
What is the origin of the greater (>) than and less (<) than signs?
A solution to an equation 2002-08-28
From A student:
How do you determine whether a pair of numbers is a solution for an equation?

If you could identify the specifics steps I need to take to determine whether it is a solution or not would be appreciated! Thanks

i.e. x-4=0 Pairs of numbers as possible solutions (4,7) (3,4) (0,-4).

Student to teacher ratio 2002-08-28
From A student:
central middle school has 2470 students and the ratio of students to teachers is 26:1 how many new teachers are needed to reduce this to 19:1?
Mixing gas and oil 2002-08-27
From Sherry:
how do I calculate the correct fuel ratio for a boat motor? 50:1 the oil containers only say how many ounces to add to 5 gallons of fuel to make a 50:1 ratio.(13 ounces to 5 gallons of fuel) I have a 20 gallon tank so what if I add 11.6 gallons of fuel, what formula would I apply to get the correct measurement of oil to add?
Common Denominator 2002-08-26
From Slobodanka:
What is a Common Denominator?
The tangent to a curve and the tangent of an angle 2002-08-26
From A teacher:
Is there a relationship between the tangent of a curve(line touching the curve at one point) and tangent (the trigonometric function)?
Divisibility of 5 2002 2002-08-25
From Simon:
I need to ask you a question if 5 2002 and 3 2002 are divisible by 26.
Express 5120 as a sum of consecutive numbers 2002-08-25
From Todd:
Express 5120 as a sum of more than 1 consecutive number.
When does an inequality represent the area above the line? 2002-08-25
From Tamara:
How do you determine that an inequality represents the area above the line and when do you include the line in the solution?
Cubic yards of concrete 2002-08-24
From Michael:
if you have a 10" dia pipe 8' long how many cubic yards would it take to fill with concrete. how how would you go about figuring it out.

and also if you would how many cubic feet, cubic inches in a cubic yard. i know you don't need to answer, seeing i am not in school, but would appreaciate it.

Sets and elements 2002-08-22
From Dianne:
I want to know why its okay to say that, for example, 6 is an element of the set of integers, but you get counted off for saying that the set of 6 is an element of the set of integers. How come?
Gallons in a cylindrical tube 2002-08-21
From Heidi:
IF I HAVE A 12" DIA TUBE WITH 1/4" WALL AND 72" IN LENGTH HOW MANY GALLONS OF WATER WILL THIS HOLD
Parallelograms 2002-08-21
From Moorthy:
11 parallel lines are intersected by another 9 parallel lines.Then how many parallelograms are formed?
The 20 kilometer walk 2002-08-20
From A student:
THE 1996 OLYMPIC GOLD METAL WINNER FOR THE 20 KILOMETER WALK WAS JEFERSON. HIS TIME WAS 1HOUR, 20 MIN,AND 7SECONDS. HIS TIME WAS NOT GOOD ENOUGH TO BEAT THE WINNER IN 1988 BY JOSEF. HIS TIME WAS 1 HOUR,19 MIN, 57 SECONDS. WHAT WAS THE WALKING RATE OF EACH PERSON?
Sole Mates Shoes 2002-08-19
From Robert:
Sole Mates Shoes has expenses of \$9,592 per month. What must the store's total income be if it is to make a profit of 12%?
When is 1! + 2! + 3! + ... + x! a square? 2002-08-19
From Sarathy:
Solve :

1! + 2! + 3! + ... + x! = y 2

How do i find the solutions ?

Combination locks 2002-08-17
From John:
How many combinations of three number codes can occur with a standard combination lock? The range of possible numbers is 0-39 which allows 40 different possible choices each turn of the dial. Each combination requires exactly three numbers (i.e. three turns of the dial). E.g. 35-40-5. Allow for reuse of the same number three times e.g.10-10-10. I don't think there is any preference shown for certain number combinations. Can you explain how the total is derived? Someone at the YMCA this week put this question to me and I gave an answer but I am not sure I am right--so I have come to you.
Volume of a sphere 2002-08-16
From Rahul:
How do i find the volume of a sphere without the knowledge of calculus?
Distance in 3-space 2002-08-16
From David:
The question is: how do I figure out the distance of one object in 3D space to another object in 3D space? I have an object at say x = 5.872, y = 2.876, and z = 7.290; and the other object is at x = 1.129, y = -8.213, and z = -11.127. I have been suggested to use the pythagorean theory on this, but since there are three variables, I don't understand how.
Probability 2002-08-16
From Chris:

There are two possible outcomes for a random event, A and B.

The probability of A being the outcome is 63%, and B 37%.

What is the likelihood that B will be chosen twice, consecutively? Three times, ten?

Variable expressions 2002-08-15
From Brittany:
I am just learning variable expressions. My homework is to write a variable expression for each word phrase;

example :

the number of minutes in s seconds
the cost of x cartons of juice at \$.75 each
And etc.

I don't understand it

A paper model of a cone 2002-08-14
From Bruce:
I have made a paper model of a cone, cut a sloping section, and removed the top. I have drawn the major and minor axis on the paper surface of the section. The major axis is not symmetrical about the minor axis. To me, this is not an ellipse. To me, an ellipse is a tubular section, because this gives a symmetrical major axis. What is your opinion?
Answered by Walter Whiteley and Chris Fisher.
The circumference of a 72 2002-08-14
From Linda:
What is the circumference of a 72" diameter circle?
Two equations 2002-07-26
From Derek:
1. 3x + 2y = 4
2. -7x + 2y = 24

finding x and y.

Some inequalities 2002-07-25
From A student:

1)-5 <= -3X+1 < 1

2)4X-2 < 6 OR X+2 > 9

Musical Scales 2002-07-24
From Terence:
Given that there are 12 notes in a musical octave, what is the maximum number of musical scales possible within that octave, if each scale has a minimum of 5 notes and a maximum of 9 and we start all the scales from the same note?

In case you don't know anything about music, a scale is a progression of notes where you start on a specific note and end on that same note an octave higher. There are twelve different notes between these two similar notes. Which notes you choose to play determine the sound of the scale. Anything less than five notes would not make for a very interesting scale. Anything more than nine and you would be playing almost 'every' note in the scale, not leaving much room for distinction in how you organize these notes.

I assume you first have to figure out the maximum number of variations possible in a 5-note scale (with 12 notes at your disposal). Then do the same for a 6-note scale, then a 7-note, then an 8-note, and so on. Then add up the results. How to find this maximum number of variations for each scale size though is what I don't know.

20 men dig 40 holes in 60 days 2002-07-24
From Lindsey:
20 men dig 40 holes in 60 days. So, 10 men can dig 10 holes in how many days?
x + 5 + x, if x = 4 2002-07-23
From Elisa:
x + 5 + x, if x = 4
7th grade math lesson plans 2002-07-23
From Peter:
Where can I get samples of 7th grade math lesson plans and curriculum for the whole year?
As much greater than 47 as it is less than 105 2002-07-23
From Joe:
To find the number in question you need to find the number exactly half-way between 47 and 105. Another way of thinking about the number that is half-way between two other numbers is as the average of the two numbers given.
Domain of a function 2002-07-20
From Andy:
I'm having difficulty in finding the domain of

1/(x2 -2x + 4)

one over x squared minus 2 x plus 4.

Percentage 2002-07-20
From Sally:
If 20% of 100 is 80, then why is the percentage difference between 80 and 100 25%.
Place six numbers around a triangle 2002-07-19
From Monika:
I need to place six numbers around a triangle, as such that one number is on each corner, and one number on each side making three numbers in one line, adding up to two hundred exactly. The number I have to use are, 40, 50, 60, 70, 80, 90. I have to use each one once, there for, each number cannot be repeated.
Answered by Claude Tardif and Chris Fisher.
Can you make up a word that adds up to 1000000? 2002-07-19
My question is elementary and I am a student Please help me with the following conundrum, as it is driving me crazy.

'When the letters in the alphabet are given values from 1 to 26 for A to Z, can you make up a word that adds up to 1000000 ( one million )-used as a multiplication?'

Like 'cat' would be 3*1*20 = 60

Order of operations 2002-07-18
From Danna:
I would like to know how to solve this type of problem; I already have the answer.

Problem: 2 [5 (4 + 6) - 2] = 96

Also, what do you call this type of problem? Thanks a lot.

Division by zero 2002-07-18
From James:
Why is division by zero undifined (i have to proof that division by zero is undifined)
A rope around a post 2002-07-15
From Nic:
My daughter who is in the 10th grade asked me this ?, you have a pole 45 inches high, 22inches around. You have a rope 1/2 thick, how many feet of rope would you use to go from top bottom of pole to top.
A probability problem 2002-07-12
From Yvonne:
What is the probability of 38 people choosing the same five options, given a choice of 15?

Perhaps you could just give me the formula with an explanation.

I am an English teacher doing educctional research, but am stuck because I don't have the math experience to help me.

Two cubes 2002-07-12
From Vanessa:
The edges of a cube are 50% as long as the edges of another cube. What percent of the volume of the larger cube is the volume of the smaller cube?
Pigs in pens 2002-07-10
From Shannon:
A farmer has 21 pigs and 4 pens, he must put an odd number of pigs in each pen, how does he do it?
Answered by Penny Nom and Chris Fisher.
The Praxis II test 2002-07-09
From A student:
1. In a class of 29 children, each of 20 children has a dog and each of 15 has a cat. How many of the children have both a dog and a cat?

2. If there are exactly 5 times as many children as adults at a show, which of the following CANNOT be the number of people at the show? a. 102 b. 80 c. 36 d. 30

3. In order to estimate the population of snails in a certain woodland, a biologist captured and marked 84 snails there were then released back into the woodland. Fifteen days later the biologist captured 90 snails from the woodland, 12 of which bore the markings of the previously captured snails. If all of the marked snails were still active in the woodland when the second group of snails were captured, what should the biologist estimate the snail population to be based on the probabilities suggested by this experiment? a. 630 b. 1,010 c. 1040 d. 1080.

A polygon inscribed within an ellipse - Part 2 2002-07-08
From Steven:
I recently sought your advice about a problem that I have been working on for eight years or so concerning a polygon inscribed within an ellipse. I think that I may have confused matters by the way in which I put the question and hope that the enclosed diagram will clear matters up. In the ellipse below I have drawn three chords inscribed within one quadrant ( this would pertain to a twelve sided figure within the whole ellipse). These chords are exactly the same length as each other, for example if the major axis of the ellipse was 360 and the minor axis 240 I have worked out that a twelve sided figure would have sides of 78.2487. However I worked this out empirically with a method that could only be described as gruelling I would be most grateful if you could tell me of a method that would work for any ellipse and any number of sides.
The base 10 multipliction table 2002-07-07
From A student:
These are two questions from Math for Elementary Teachers and they have me stumped.

You have two coins that are worth 30 cents. One of the coins is not a nickel. What are the two coins?

The product of the diagonals of any 2x2 matrix in the base 10 multiplication table are equal. Why?

A box that holds 22.4 liters 2002-07-07
From Jon:
How do I find the measurements required to make a box that holds 22.4 liters of something?
Equivalence relations on a set of cardinality n 2002-07-06
From Siddhartha:
what is the no. of equivalence and transitive relations on a set of cardinality n?
An equalateral polygon inscribed within an ellipse 2002-06-30
From Steven:
How would you calculate the length of one of the sides of an equalateral polygon (of n sides) inscribed within an ellipse ( of any eccentricity ) where all of the vertices exactly touch the perimeter of the ellipse?

I know that when the eccentricity is zero ( i.e a circle ) the formula: r * (sin(180/n) * 2) will suffice. But what about when the eccentricity is greater than zero?

Math test 2002-06-28
From Dustin:
I have a really important placement test to take in 2 weeks. I need to have a strong comprehension of algebra and I have't taken a math class in about for years.

I'm 24 and am going back to school. I want to get ahead and into math 96, and must pass this test to do that.

Do you know of a book or a wab site that can teach me a few formulas that will give me the edge I need. If I have the right text for the job i'll study day and night to pass.

Future value 2002-06-27
From Susan:
If one were to invest \$115 a month for 20 years and expect a 4% annual return, what is the value of this money in 20 years?
What is the next term? 2002-06-21
From A student:
What is the next term in the sequence:

1, 5, 14, 30.....

Counting 2002-06-21
From Rachel:
How many different numbers of 2 different digits each can be formed using the digits (1,3,5,7,9)?

How many triangles are formed by the vertical of a regular hexagon?

Jack and Jill wrote letters 2002-06-19
From Angel:
jack and jill each bought a stationary
# of sheets of paper in each box were the same
# of envelopes were the same
jill wrote letters consisting of 3 pages
jack wrote letters consisting of 1 page

when they wrote all letters jill had 50 envelopes left and jack had 50 sheets of paper left how many pieces of paper and how many envelopes?

Integrating x^x 2002-06-18
From Jeremy:
I am a student at the University of Kansas and I am wondering if there is a general anti-derivative for x x (i.e. the integral of x x dx)? I've looked in a bunch of Table of Integrals and have found nothing (can you guys find it?), so I'm sort of wondering if this may be a research type question.
A good rule of thumb when driving 2002-06-13
From Lisa:
A good rule of thumb when driving is that you should be about one car length away from the car in front of you for every 10 miles per hour that you are travelling. Suppose you follow this rule perfectly (so you are exactly the correct distance away). You are waiting at a stop light with your front bumper just touching the car in front of you. The light turns green and the car in front accelerates at a constant rate "r". Calculate how you should accelerate in order to follow the rule.
The cross country team 2002-06-12
From Denae:
In cross country, a team's score is the sum of the first five finishers on the team. The captain of the team finished 2nd in the meet. The next four finishers on the team placed in consecutive order. The team score was 40. in what places did the other members finish?
An equilateral triangle 2002-06-11
From Sarah:
Hi. My name is Sarah. I'm a secondary student taking a Math 30C course by correspondence. The question has two parts.

The first part is: Draw an equilateral triangle XYZ. Draw the altitude from X to YZ. Choose any point P inside the triangle or on the triangle. Draw perpendiculars from P to the sides of the triangle. The Second part is:

Measure the altitude h and the 3 perpendiculars s, t, and u to the nearest mm. Repeat as many time as is necessary until you can state a generalization concerning h, s, t, and u. If you could help me, it would be greatly appreciated.

Drawing cards 2002-06-11
From Ed:
What is the probability of drawing without replacement from a standard deck of 52 cards the following 5 card hand ...... the ace of spades, 2 tens and 2 face cards

Solution 1: 1/52 x 4/51 x 3/50 x 12/49 x 11/48

Solution 2: Using Combination theory ..... (1C1 x 4C2 x 12C2) divided by (52C5)

Can you help us understand which answer is correct and why the other is not?

Successive coefficients in the nth row of Pascal's Triangle 2002-06-10
From Tim:
There is a formula connecting any (k+1) successive coefficients in the nth row of Pascal's Triangle with a coefficient in the (n+k)th row. find this formula.
0.63 of an acre 2002-06-08
From Sherry:
how many square feet are in 0.63 of an acre
Regular polyhedra 2002-06-07
From Sandra:
The other day a colleague and I were talking about polyhedra. Is regular a term applied to polyhedra or just polygons? If so, then what would define a regular polyhedron? Would it mean all faces are regular or would it mean that all faces are identical and regular? That is, could a pyramid with equilateral triangles for lateral faces and a square base be considered regular or must the base also be an equilateral triangle?
The mean distance travelled 2002-06-07
From A student:
If Rosalia travels 1000 km
Sheree travels 280 km
Daniel travels 50 km
Mica travels 200 km
Connor travels 500 km
Eric travels 250 km
Hillary travels 300 km

What was the mean distance travelled?

How do you arrive at the answer?

Constructing the square root of 3 2002-06-07
From Allan:
I am a Math 7/8 teacher. I was wondering how you would show a student how to find the exact location of the square root of three on the number line using just a compass and a straight edge.
Perimeter 2002-06-05
From Tava:
I'm a grade four student from St. Mary school. In class we've been dicussing perimeters. So this is what we did; First we each got a piece of paper in the shape of the geoboards and our teacher told us to find as many different shapes of area of 12 square units. During this time we were given to find perimeters of shapes that had twelve square units one of our classmates discovered the biggest perimeter possible with twelve square units of 26 units. Another classmate discovered the smallest perimeter of fourteen units. Here's a question: Why are all the shapes with fourteen units all the same shape? and why are all the shapes with twenty-six units can be different? After we found the biggest and smallest shapes our teacher told us we each had to find at least one shape of the biggest and smallest. After we each foud a shape with a perimeter of twenty-six and fourteen we had to find different shapes with different perimeters. During that time we discovered different perimeters.

What we found was fourteen all the way up to twenty-six, but they all went by two's. Why didn't they count up by 14, 15, 16, 17, 18 etc? I think it's because the area is an even number. See if you added one "block" or "square" to it you always add three because at least one of the sides is together with another side. Whyare all the perimeters all even numbers?

A polynomial 2002-06-05
From Melissa:
I'd like to know what is a polynomial( the definition and an explication)? And is 7x a polynomial? and why?
The area of a circle 2002-06-03
From Jessica:
I am doing a maths assigment for university, which is aimed towrds primary school students(k-6). I was wondering if you could give me some information as to how I could describe to students the rule for finding the area of circle, using a circle cut up into equal sectors (like a pizza). I know it has something to do with the fact that you can make these shapes into a parallelogram, but I am a bit uncertain as to how I can express this idea clearly and articulately to students.
Ratios and weights on Neptune 2002-06-03
From Janice:
The ratio of an object's weight on earth to it's weight on Neptune is 5:7. How much would a person who weighs 150 pounds on earth weigh on Neptune.
Ounces and cubic centimeters 2002-05-30
From Martin:
How many ounces are in 600cc of liquid?
11........1 2002-05-29
From Un eleve:
Démontrer que tout nombre impair non multiple de 5 admet un multiple de la forme:11........1
Conics 2002-05-29
From Brooke:
Which conic cannot be generated by an intersection of a plane and a double napped cone?
Overlapping circles 2002-05-29
From Naman:
There are two circles, big circle with radius R and small one with radius r. They intersect and overlap in such a way that the common area formed is 1/2 pi r 2 (half the area of the small circle) If r=1, find the Radius of the big circle (R)?
The sum of the areas of two regular decagons 2002-05-27
From A parent:
The sum of the areas of two regular decagons is 39 square inches, and their radii are in the ratio of 2:3. Find the area of the larger decagon.
Linear programming 2002-05-27
From Jes:
A machine shop makes two parts, I and II, each requiring the use of three machines, A, B, C. Each Part I requires 4 minutes on Machine A, four minutes on Machine B and five minutes on machine C. Each Part II requires five minutes on Machine A, one minutes on Machine B and six minutes on Machine C. The shop makes a profit of \$8 on each Part I and \$5 on each Part II. However, the number of units of Part II produced must not be less than half the number of Part I. Also each day the shop has only 120 minutes of machine A, 72 minutes of Machine B, and 180 minutes of Machine C available for the production of the two parts. What should be the daily production of each part to maximize the shop's profit?
Cubic feet and cubic yards 2002-05-27
From John:
how do you find the cubic feet/cubic yard of area 10 feet wide by 15 ft long by 2 inches high
One-fourth of a number is added to one-third of the same number 2002-05-26
From A student:
When one-fourth of a number is added to one-third of the same number, the result is 28. What is the number?
A spotlight shines on a wall 2002-05-25
From Barb:
A spotlight on the ground shines on a wall 12m away. If a man 2m tall walks from the spotlight toward the bldg at a speed of 1.6 m/s, how fast is his shadow on the bldg decreasing when he is 4m from the bldg?
A schedule for 24 golfers 2002-05-25
From John:
I am working on a schedule for 24 golfers. 6 groups of 4. I have 8 golf days (twice per week for a month).

Ideally, I would like to schedule all 24 golfers in 6 different groups of 4 on each day. Here is the catch.....no golfer in any group can be grouped togther more than once. Every group of 4 each day will have 4 new golfers that have never played together before. Is this possible?

| n + 4 | + | 3 - 2n | = 16 2002-05-24
From Randall:
I don't seem to be able to solve this: | n + 4 | + | 3 - 2n | = 16
Blood donations 2002-05-23
From Fiza:
One particular high school encourages students to donate blood. the high school gym is set up for purpose. the distribution of blood type in north america is as follows.

Type O:44%
Type B:10%
Type A:42%
Type AB:4%

(a) what is the probability that the first two people in the line up have the same type of blood?

ANSWER: I donn't know how many people are in the line. so how can I answer this question.

(b) what us the probability thar none of the first five people in the line up have type AB blood?

3 radians subtends an arc of 27 meters 2002-05-22
From Kyle:
In circle O, a central angle of 3 radians intercepts an arc of 27 meters. Find the number of meters in the length of the radius.
Bob swam across a river 2002-05-22
From Torri:
Bob swam across a river 420 ft wide. A strong current carried him 580ft downstream as he swam. Find x, the distance bob actually swam.
Telephone banking 2002-05-22
From Fiza:
To use telephone banking to pay bills, the customer has to enter the last three digits of each bill. the numbers 0 to 9 can be used. if the number happened to be the same on more tan one bill, the customer has to enter the first three digits as well.

(a) what is the probability that a person has 2 bills to register with the same last three digits?
ANSWER:P(2 bills to register)=1/10P3 1/(10!/7!), 1/(10*9*8)=.001389

(b) what is the probability that a person with 10 bills to register has at least 2 bills with the same last three digits?

The average of two averages 2002-05-22
From RJ:
in a class with 22 students, the average garde on an exam was 68%, in another class with 32 students, the average grade on the same exam was 78%, what was the overall for the two classes? round your answers to the nearest whole number.
Un octogone 2002-05-21
From Yves:
Si j'ai un octogone ayant 8 pieds de diamètre,comment fais t'on pour trouver la mesure de un de ces cotés et quel est cette grandeur.
A popular television game show 2002-05-19
From Amrita:
On a popular television game show, contestant must first answer a question by placing 4 given events in ascending or desending order in the quickest time.

(a) if a contestant does not know how any of the events should be arranged, how many different ways could the question be answered?

(b)a contestant has to arrange the events that correspond to A, B, C, and D. one contestant is positive that event D follows directly after avent B, but does not know about the other s. how many different ways could this contestant arrange the letters A, B, C, and D, list the possibility

Probability and investment 2002-05-19
From Bally:
Investors do not invest all their money in the investment predicted to be the best beuause it is too risky. an investor holds shares in three independent cmpanies. company A, Company B, compnay C. an analyst predicts the probability of profit increases for each company as follows. Company A:0.70 Compamy B:0.50 Compnay C:0.65

(a) If the analyst's predictions are true, what is the probability that all three comapanies show a profit incresse?

ANSWER: I try using vin diagram but it did'nt work, I dont know any other ways to solve this question

(b) if the analyst's predictions are true, what is the probability that at least one comany shows a profit increase?

Conditional probability 2002-05-19
From Manny:
In a certain school, it is known that 80% of the students use the internet for school projects, 60% use e-mail on a regular basis, and 90% use the internet for school projects or for e-mail on a regular basis. a student from this school is selected at random

Determine thge probability that the student used e-mail, given that the student used the internet for school projects.
ANS: how can i solve this question by useing the vin diaagram

Flying with the wind 2002-05-19
From SaraJean:
It takes 6 hours for a plane to travel 720 km with a tail wind and 8 hours to make the return trip with a head wind. Find the air speed of the plane and the speed of the wind current.
How far apart are the transmitters? 2002-05-18
From Jeff:
A ship at sea is 70 miles from one transmitter and 130 miles from another. The measurement of the angle between the signals is 130 degrees. How far apart are the transmitters?
Find the angle measures 2002-05-18
From Amanda:
In triangle ABC; the measure of angle A is 20 degrees more than twice the angle B. The measure of angle C Is five times angle B. Find the angle measures.
Chord length 2002-05-17
From Ashlie:
How do you find the chord length of one section of a chord if you only have the diameter length and the other whole chord length.

WV is the diameter and equals 16. XY is perpendicular to it, and equals 10. They intersect at pt. Z. I need to know what WZ equals. Please help!

On which assignment did I do better 2002-05-17
From Denise:
I have 2 writing assignments in class. The first assignment, which had a mean of 10 and a standard deviation of 2, I got a score of 12. The second assignment had a mean of 18 and an s.d. of 3, I got a 21. I need to know which assignment did I do better, relative to my classmates?
Sequences that agree on their first four terms 2002-05-16
From Mike:
Are there two formulas that define sequences that agree on their first four terms, but differ on the fifth term and all succeeding terms?
From Navi:
Children usually attend birthday parties where a thank you gift is given to the children who attent the party. a family likes to hand out books at thank-you gifts.

(a) One child invited to the party is given 2 books as gift. if there was 15 different books to choose from, how many diffrent gifts were possible?

Answeer: I did this way 15C2=105

(b) if the 15 books consisted of 8 nonfiction and 7 fiction, how many diffrent gifts were possible if at least 1 of 2 books were fiction?

Day care 2002-05-13
From Sonam:
In many familes, both parents work. as a result, there is increasing need for day care. data was collected; and in one year in Canada, approximately 32% of children aged 0 to 11 years were in day care for at least 20h per week.

(a) what is the probability, in a random poll of 60 children form the age of 0 to 11, that more than 15 children are in day care at least 20 h per week? nearest tenth of one %

P(children are in daycare at least 20h)= 60/60C14 = to the answer

(b) what is the probability, in a random pool of 60 children that fewer than 20 are in day care at least 20 h per week?

P= 20/60= 33.3% stay in day care for 20h per week,

From A student:
I am a high school senior and have to write an essay answering the question "What is Calculus?" I need some ideas. Thanks
A game of dice 2002-05-13
From Mika:
To play a game a dice is rolled to see who plays first. four players are going to play the game. what is the probability that at least two people roll the same number?

ANSWER: P(least 2 people roll the same #)=number of player/total outcome

P = 4!/4C2 = 24/4C2 = 4 the answer is 40%

An award ceremony 2002-05-13
From Mika:
Five students are equally qualifide their school at an award ceremony. two students will be randomly chosen to go to the ceremony.

(a) if Tony is one of the five student, what is the probability that he will be chosen?
Ans: 2/5C2=0.2 which is 20%

(b)Tony's friend, Allecia, who was also eligible to go, has been chosen. what is the Tony's probability of being chosen after he learns that allecica is going:
Ans: 1/5C1=0.2

Some algebra 2002-05-11
From A student:

/x - 2 ^4/x = 8

/ = square root sign
^ = 4th root of x

also, dividing
2x3 -3 -6x
__________
4 + 2x

the 2x3 is 2x to the third

A ski trip 2002-05-10
From Navi:
A ski trip at the school has been arranged. there are 30 students that have paid for the trip and 6 parents that have volunteered to chaperone. to transport the students and parents easily, they are to be divided into two group. one group has 10 students and 2 parents, and the other group has 20 students and 4 parents.

(a) How many different group of 10 students can be formed?

(b) How many different groups consistinmg of 10 students and 2 parents are possible?

(c) kelly is one of the students going on the ski trip, and kelly's mother volunteered to be one of the chaperones. kelly's mother would prefer to be in the smaller group and not in the same group as kelly. if this wish is honoured, how many ways can the smaller group and its chaperones be chosen?

The law of cosines and obtuse angles 2002-05-09
From Bryant:
The question that I am pondering is that I need to derive the law of cosines for a case in which angle C is an obtuse angle.
A rectangular marquee 2002-05-07
From Alyaa:
a marquee with rectangular sides on a square base with a flat roof is to be constructed from 250 meters square of canvas. find the maximum volume of the marquee. i find this topic so hard
Forming a committee 2002-05-06
From Navi:
A committee is to be formed to investigate what activites teenagers have available in small communities. the committee is to have 7 members, chosen randomly form interested community members. there are 10 parents, 5 teenagers, and 4 adult without children who have all expressed an interest in serving on the committee.

what is the probability that the adults without children are all on the committee?

Answered by Andrei Volodin and Penny Nom.
Oven lights 2002-05-06
From Manny:
Q.A manufacturer of stoves has to buy oven lights from from two diffrent companies because one company alone cannot meet its demand. the manufacturer purchases 60% of the oven lighs from comany A and the rest form Company B. Past experiecnce shown that 1% of Company A's oven are defective oven and 2.5% of Company B's oven light are defective.

Determine the probability that a defective oven light is supplied by company A.

How will I use calculus in my career? 2002-05-06
From Meridith:
How will I, hopefully a future secondary mathematics teacher, use calculus in my career if I'm not teaching calculus?
3 = -2x 2002-05-05
From Timothy:
My question is 3 = -2x

How do I isolate the variable here?

A probability tree 2002-05-04
From A student:
Karl and Naomi roll three dice. Karl gives \$10 to Naomi if the number 5 turns up once, twice or three times. Naomi gives Karl \$3 in all other cases. A) construct the probability tree for this situation.

My problem is I am unfamiliar on how to draw this probability tree and seem to be having a lot of difficulties, when you have a chance please answer this math problem and get back to me with the results.

An identity(?) 2002-05-02
From A student:
prove identity sin 2x/1-sinx= secx+1/secx

8/13*26/27 2002-05-01
From Arias:
8/13*26/27=
Square numbers 2002-05-01
From Sally:
Is one considered a square number?
oneths 2002-04-30
From Logan:
why are there tens-tenths hundreds-hudreths, but not oneths

if that made no sense then how about this why does everything have two ways of saying things like tens and tenths but not a oneths

Factor 12x^2 - 20x - 8 2002-04-30
From Crystal:
Factor Completely: 12x2 - 20x - 8
The Dugout, Don's Basement, Cd Corner,... 2002-04-30
From A student:
The Dugout, Don's Basement, Cd Corner, Harry's Deli, Bill's Software, Anne's Footwear, and Joanne's House cleaning.

The gift certificates are each in multiples of \$5. There is a \$100 range in the value of the gift certificates, which start at \$25. The mean value of all seven gift certificates is \$80, and the median and mode are both \$70.

The certificate from The Dugout is worth the most and the one from Joanne House cleaning is worth the least.

The total value of the gift certificates from CD Corner, Harry's Deli, and Anne's Footwear is \$270, but Anne's Footwear certificate is worth \$50 more than the one from Harry's Deli. The Cd Corner gift certificate is equivalent to the mean for this group of three.

What is the value of the gift certificates from each store?

What's the next term? 2002-04-29
From A student:
Find the nth term for the following:

1) 12, 30, 56, 90, 132
2) 6, 30, 84, 180, 330
3) 8, 15, 24, 35, 48
4) 10, 17, 26, 37, 50
5) 24, 40, 60, 84, 112
6) 24, 60, 120, 336, 504

Please show the FULL working out.

Trains and cracker boxes 2002-04-29
From Lindsay:
1)Two trains are 250 miles apart on the same track heading towards eaxh other at 7AM- The first train travels at 55mph, the second at 75mph. At what time would they crash?

2)A cracker box measures 12 by 2 by 18 inches. The company wants to double the amount of crackers, but keep the shapes the same[similar] Find the new length[nearest tenth of an inch]

Conversion of units 2002-04-29
From Matt:
I am having trouble finding a workable equation for the following problem, particularly the conversion of two systems of measurement.

The question states that there are 27 grams of salt in a kilogram of seawater. And it asks how many tonnes (1 tonne = 1000 kilograms) of salt are there in one cubic kilometer of ocean. It also says that the density of seawater is 1.1 g/cm3.

What is the equation and how do I figure out how many kilograms there are in a cubic kilometre?

A 6,000 gallon tank 2002-04-28
From Someone with a big tank:
I was wondering if you can find out information about how much liquid fuel can fit in a 6,000 GAL. tank. Right now I do not have the exact dimensions of this tank but I will have it the 29th of April. Could you please E-mail me and let me know if you can answer this question after I have the correct specifications.
0/4 = ? 2002-04-28
From Danielle:
I am embarrased to be asking this question, but... is it possible to have a fraction with a zero? For example, 0/4. This does not make sense to me and I do not know what it would be representing, other than nothing! Is it proper to express such a fraction?
A triangular prism 2002-04-28
From A student:
Need the formula for the surface area of a triangular prisim?
a+b=10 and ab=40 2002-04-27
From April:
What two numbers add to ten and multiply to forty?

(a+b=10, a*b=40)

Designing a ballot 2002-04-26
From Kelley:
I want to design a ballot for four elections. Actually all the candidate races are on 1 ballot. I need to know how many different ballot styles would be needed for all of the candidates to be in each rotation an equal number of times.

For example:

• A,B,C & D are running for mayor

• E,F,G & H are running for congress

• I,J & K are running for senate

• L,M & N are running for governor

They are all on the same ballot. But in each race their name (for instance A) has to be in the #1 rotation, #2 rotation, #3 rotation, and #4 rotation for his race on this ballot an equal number of times as B,C and D.

The same goes for the other candidates for their perspective races.

How many total ballot styles will there be?

Triangular numbers 2002-04-26
From Anika:
Can you please tell me what a triangular number is?
Functions and relations 2002-04-25
From Erin:
Here's a few math problems that might drive a person insane ;)
1. If 2f(x) - 3f(1/x) = x^2 what is f(2)?

2. What are the domain and range of the following relations?
• x^2 - 4y^2 = 25
• 4x^2 + 9y^2 = 36

3. The port of Swan Harbor is 200km away from Merry Town Inlet on a bearing of N50E from Merry Town. A ship leaves Merry Town at 8am and sails N15W at 15 km/h. At the same time, a second ship leaves Swan Harbour on a course of S80W at 20km/hour. How close, to the nearest km, are the two ships at 13:00?

4. Prove the identity. 1+sinx + cosx/ 1-sinx + cosx = 1+sinx / cosx

How much of that total is G.S.T? 2002-04-24
From Darlene:
If I have \$1700.00 how much of that total is G.S.T?

not 1700.00 + gst

____ + _____ gst = 1700.00

Arithmetic progressions 2002-04-24
From David:
I have been searching everywhere for the formula to mathamatical progression.
From Aurora:
I wrote a mathematical Olympiad the other day and there was one question that I could not work out.

The question was If ab = 1, bc =2, cd =3, de =4 and ea = 6, what does a + b + c + d +e =

It was a multiple choice and the answers were : 43/6; 47/6; 49/6; 53/6; 61/6 The correct answer was 61/6, but how can do you get to that answer?

A test drive 2002-04-23
From Jennie:
At 9 A.M. a test car driving at a constant speed passes a marker 50 miles from it's starting point. At noon the car is about 130 miles from the marker. If the test drive ends at 1:30 P.M., how far will the car be from its starting point?
25m = 100 2002-04-22
From Megan:
If 25m = 100, Then m equals what number?
Lines of symmetry 2002-04-22
From Cindie:
How many lines of symmetry do the following figures contain?

trapezoid:

rhombus:

hexagon:

pentagon:

Problem solving 2002-04-20
From Kathy:
1. Zachary wanted to run the shore-to shore marathon next month, a 26 mile race from one side of the island where he lived to the other. He decided to work up to 26 miles by running five days a week for the next five weeks. Each day he'd run one mile longer than he did the day before, except for the first day of the week, when he'd run the same number of miles he ran on the last day of the previous week. He wanted his last two practice runs to be 26 and 27 miles long.

How many miles would he have to run on his first practice run?

2. A school just bought a new set of encyclopedias. The front and back covers are 1/8 inch thick, and the pages are 1/100 inch thick (in other words, there are 100 pages per inch). the 26 volume set has a total of 5,250 pages. If you assume there is no extra space left between books, then .........

What length of bookshelf will the encyclopedias take up?

Solve for x 2002-04-20
From A student:
solve for x.
`  c-x      2x+b ----- = --------   a        c `

Cubic yards 2002-04-20
From Pat:
I HAVE AN AREA 10'x6'I WOULD LIKE TO PUT LOAM ON IT 5" DEEP HOW MANY CUBIC YARDS OF LOAM DO I NEED?
An augmented matrix 2002-04-20
From A student:
Hi my math teacher asked us to solve an augmented matrix. I am in twelfth grade and need help. The book we are working on is college algebra. Here it is

a+2b+c=0
2a+5b+4c=-1
a-b-9c=-5

Solving for x 2002-04-19
From Susan:
I'm having a little trouble solving these equations for x. I can't seem to separate x fully from the other numbers. Please help! Here are the problems:

(2x-1)/(x-2)(x 2+3) = 0 and

y/(x+1)=z/x

Moving a triangle 2002-04-18
From A student:
find the verticles of a triangle after it is translated 2 units to the left and then is reflected across the graph of y=x+2. The original verticles of the triangle are (2,0), (3,2), and (6,2).
How many different account numbers are possible? 2002-04-18
From Andrene:
how many different account numbers are possible if the account numbers consist of a letter of the alphabet, followed by five numerical digits, and followed by another letter.
Arc length 2002-04-17
From Vix:
Find the point on the curve r(t)=(12sint)i-(12cost)j+5tk at a distance 13pi units along the curve from the point (0,-12,0) when t=0 in the direction opposite to the direction of increasing arc length.
Ratios 2002-04-17
From A student:
1. Medication is givin at 1cc. per 20 pounds of body weight. A dog weighs 16 pounds how many ccs. of medication does the dog get?

2. Dr. Lee wants you to prepare 1000 ml. of a 10% dextrose solution in lactaed ringers for diuresis or a patient you have a 1 L bag of lactated ringers and 500 ml of 50% dextrose for injection. How would you prpare the solution?

Related rates 2002-04-17
From Molly:
A tanker spilled 30 ft cubed of chemicals into a river, causing a circular slick whose area is expanding while its thickness is decreasing. If the radius of the slick expands at the rate of 1 foot per hour, how fast is them thickness of the slick decreasing when the area is 100 feet squared?
Two algebra problems 2002-04-14
From Ashley:
Question 1: For all values of a, let < a > be defined as < a > = 4a - 4 . Which of the following equals < 6 > - < 5 >? A: < 2 >
B: < 3 >
C: < 4 >
D: < 5 >
E: < 6 >

Question 2: If 5n + p = 3 and 2m - 10n = 2, what is the value of m + p?

A polynomial 2002-04-14
From A student:
A polynomial function is described by the following conditions: f(x) has two real zeros at x= -2 and x= 1, each of multiplicity 2 f(x) has two complex zeros as x goes to -infinity, f(x) goes to +infinity as x goes to +infinity, f(x) goes to +infinity f(x) has a y-intercept at (0,2)

Sketch a polynomial function that satisfies the above conditions.

Write an equation for function f(x)

Write another function g(x) that also satisfies the above parameters.

How many gallons of water in a cubic foot? 2002-04-14
From Richard:
I am tring to find out how many gallons of water in a cubic foot.
The vertex of a cone 2002-04-13
From Callie:
Does a cone have a vertex?
The square root of four 2002-04-13
From Frank:
In a recent quiz we where asked the square root of four. The quizmaster gave the answer as not only 2 but also -2. Being pedantic I queried this. Although -2 squared is 4, does it follow that the root of 4 is -2 Can you enlighten us?
Answered by Claude Tardif and Penny Nom.
The bleep test 2002-04-13
From Lorraine:
I am currently undergoing training and have asked about a fitness test called the bleep test. The bleep test involves running continuously between two points that are 20m apart. These runs are done in time to a pre-recorded bleep sounds on a pre-recorded audio cassette. The time between the recorded bleeps decrease after each minute. I would like to do my own personal version for training but I have to work out the following before doing this:

I need to find out the time in-between the beeps at least for the first level so I can work out the difference for the other levels:

The information given to me for the first level is :

A 20 meter run at 8.5km/hr (how long would it take?)

Please let me know if there is any way in working out this query with the information given.

Calculate profit 2002-04-13
From Allison:
If I sell something for \$75; and my cost is \$40, I make \$35 profit. How do I calculate the profit percent I made on that transaction?
Diagonals in a polygon 2002-04-10
From Murray:
If you have a regular polygon with n sides and you draw all (n-3)n/2 diagonals how many intersection will they form with each other and how many sections will they devide the polygon into.
Answered by Caude Tardif and Chris Fisher.
n +1, n+2, n+3, and n+4 are all composite 2002-04-09
From Jonathan:
Find the small integer n such that n +1, n+2, n+3, and n+4 are all composite
The Proof in the Pudding 2002-04-09
From A student:
The host at a party turned to a guest and said, "I have three daughters and I will tell you how old they are. The product of their ages is 72. The sum of their ages is my house number. How old is each?" The guest rushed to the door, looked at the house number, and informed the host that he needed more information. The host then added, "The oldest likes strawberry pudding." The guest then announced the ages of the three girls. What are the ages of the three daughters?
Sodding the yard 2002-04-08
From Craig:
my parents want to lay sod in our back yard.

the sod cost \$2.00 per square foot.

The size of our yard is 20x20 and 26x41

Area of a triangle 2002-04-07
From Puzzled:
What is the surface area of a triangle 13 ft x 13 ft x 18 ft?
3/4n-6=12 2002-04-07
From Diane:
I am in 6th grade advanced math and I just started Algebra. My teacher tries to explain it to me but I just can't get it. I am having difficulty understanding it. Please HELP!!! I will type a problem, if you could answer it and show your work so i can understand it that

would be great. Please explain in simple terms.

here is a couple problems I am having trouble with,

PROBLEM #1

3/4n-6=12

Composition of functions 2002-04-06
From Yvonne:
In our new text book, the following question occurs: State the domain and range of g(f(x))given that f(x) = -x2 - 4 and g(x) = sqrt(x)

The range of f(x), x<=-4, is the domain of g(x). BUT, there is no solution in the Real numbers for g(f(x))= sqrt(-x2 - 4).

In the solutions it says that this is not a function and therefore does not have a domain or range. Is it a relation? Is it anything?

Pairs of equations 2002-04-04
From A student:

high school level

```y=4x x=-4y
x+y=5 3x+2y=20

y=x-1 3x-y=4
x+y=3 2x-3y=-9

x+5y=4
3x+15y=-1

. . .
```

Two triangles 2002-04-03
From Scott:
Consider 2 triangles: Triangle PMB and Triangle PLA.

Triangle PLA is contained within Triangle PMB.

Side LA is parallel to Side MB.

Point L is located on Side PM. Point A is located on Side PB.

If the ratio PL:LM = 5, then what is PB:PA ??

Take It! 2002-04-03
From Bryan:
You are playing Take It! for \$180,00 with a total stranger. There are 180 identical balls in a big vase. Each player in his turn, reaches into the vase and pulls out 1,5,or8 balls. These balls are discarded. The player who takes the last ball from the vase wins the \$180,000. A flip of the coin determines that you will go first. Are you glad? How many will you take out on the first move, and how will you proceed to win the prize?
Common fractions to decimal fractions 2002-04-02
From Natalie:
My questions are: "how can I change 23/60 into a decimal. and give my answer to 2dp."??????????

2nd question:for each of these pairs, which is bigger?

4/7 or 36%____________
3/11or 0.29____________
14/24 or 0.57___________

Pascal's Triangle 2002-04-02
From Brian:
It's about (a+b)x. I remember there a triangle with numbers to remember for a faster solution. Can you please teach me?
If you conect all the vertices of a regular n-gon... 2002-04-01
From Murray:
If you conect all the vertices of a regular n-gon with lines you will have (n-3)(n/2) lines inside the polygon. I want to find out how many sections these lines divide the polygon into and how many intersections they have with each other.
Area of an octagon 2002-04-01
From Someone:
What is the actual square footage of a 12' octagon?
All four eights in three consecutive hands 2002-04-01
From Blair:
What are the odds against the same person holding all four eights in three consecutive hands.
Meg's biscuits 2002-03-29
From Tami:
Meg's biscuits recipe calls for 4 cups of flour for every 1.5 cups of milk. If Meg uses 6 cups of flour, how many cups of milk will she need?
The reciprocal of a decimal mixed number 2002-03-29
From A student:
How do I find the reciprocal of a decimal mixed number?
Some 5 card hands 2002-03-28
From A student:
From a standard deck of cards how many 5 card hands are possible consisting of a. exactly 4 hearts

b. two cards of one kind and three of another(like a full house).

100 from four 9's 2002-03-27
From A student:
My teacher gave us a math problem to try and figure out and I am stumped. The problem was this.... by only using four nines, how can you get an answer of 100? You can add, subtract, multiply or divide...anything you need to do ,but you can only use four nines.
If the matrix A is inverible and AB =AC, then B = C 2002-03-27
From Vikki:
i hope you can help i am soooo stuck here goes:

a)

` A= 0 1 B= 1 1 c= 2 5    0 2    3 4    3 4 `
A,B and c are matrices

Evaluate AB and Ac (which I can do)

then

b)
I need to prove that if the matrix A is inverible and AB =AC, then B = C. Why does this not contradict what happened in part a)?

Cube roots 2002-03-26
From Kathy:
My son is in 4th grade and needs to simplify the cube roots of 216, 512 and 64. How does he do this with a regular calculator or without?
A triangle in a circle of radius 6 2002-03-26
From Marko:
In a circle of radius 6, a triangle PQR is drawn having QR = 8 and PQ = 10. Determine the length of PR
A lottery question 2002-03-25
From Noel:
I want to take all numbers in a Lotto game from 1 to 45 and ditribute them between 9 boxes each containing 5 numbers. Each number is used only once.
1. What is the probability that I derive the correct combination of 5 numbers in the draw?

2. What is the probability if I take a systems game and now distribute 9 numbers into each of 5 boxes? Once again, the numbers are used only once.

3. Can you explain what formulae are used and how the answer is derived? Is this a distribution or combination problem? Or is it a combination of both distribution and combination?

Answered by Andrei Volodin and Penny Nom.
Unit fractions 2002-03-23
From Laura:
Write 1/2 as the sum of ten different unit fractions.
A hamburger and a soft drink 2002-03-23
From A student:
A GROUP OF FRIENDS WENT OUT TO LUNCH. EACH BROUGHT A HAMBURGER AND A SOFT DRINK. TOGETHER A HAMBURGER AND A SOFT DRINK COST MORE THAN A DOLLAR. THE TOTAL COST FOR THE GROUP WAS \$17.81. THERE WAS NO TAX OR TIP INCLUDED.

IF A HAMBUGER COSTS 2 CENT MORE THAN TWICE A SODA, FIND THE COST OF THE HAMBURGER.

A probability problem 2002-03-23
From Kate:
If I have a spinner and then spinner has the numbers 1,2,3,4 on it and it is spun 3 times, what is the probability that the spinner will stop on 4,3,and 1 ? In that order?
A trigonometric identity 2002-03-22
From Debby:
I am stuck on a problem and wondering if you can help?? It is: Prove the following:
sec2(X)+csc2(X) = sec2(X)csc2(X)

Mr. Byrd's drive to work 2002-03-22
From Mr. Bollen:
Mr. Byrd leaves his house at 7:00am to go to work. If he drives 40 mph he will arrive 3 minutes late and if he drives 60mph he arrives 3 minutes early. At what speed will Mr. Byrd have to drive in order arrive exactly on time. Please describe how you arrived at your answer.
Answered by Claude Tardif and Penny Nom.
Range of values for standard deviation 2002-03-22
From Susan:
What is the range of values for standard deviation? Is it between 0 and +3? Is it between +1 and +3?
What fraction of the world's motor vehicles are built in Canada? 2002-03-20
From A student:
About 1/4 of the world's motor vehicles is built in Canada or the United States. About 1/5 of the world's motor vehicles are built in the United States. What fraction of the world's motor vehicles are built in Canada?
From Dolores:
I get totally confused with this problem. I get confused with the getting the lowest terms.

4/x-5 + -2/x -10/x^2-5x

A cone in 3 space 2002-03-20
From Matthew:
Let C in R3 be the cone defined by x2 + y2 - z2 = 0

(A) Let P be the plane described by x + 2z = 1

(i) Find a description of P in terms of two parameters s and t

.
.
.

F = -3 + 3 2002-03-19
From Jessica:
F= -3 + 3 WHAT IS F?????
A set of points in space 2002-03-18
From Victoria:
Describe the given set with a single equation or a pair of equations:

The set of points in space that lie 2 units from the point(0,0,1) and at the same time 2 units from the point (0,0,-1).

24x^4 + 3x 2002-03-18
From gary:
24x 4 + 3x
Interest owing 2002-03-17
From Dean:
I am an investor. If I lend to someone on January 1, 1999, \$1000 to be paid back interest at 2% per year (simple interest, ie not compounded), and on July 15, 1999, I lend the same person \$1,500 more (total loan is now \$2,500) but at 18%, and once again on October 15, 1999, I lend to the same person another \$1,500, and the person pays me back the principle(\$4,000) and interest on January 1,2001: What is the total (principle plus interest) due me? The tougher question is: what was my blended rate of return on my total outlay of money? Is there a formula you can give me so that I can perform my own calculations?
Combinations? 2002-03-16
From Sara:
A combination lock has three dials numbered 0 - 9. Give a mathematical reason why "combination" is a bad name for this type of lock.
Answered by Penny Nom and Chris Fisher.
How much olive oil? 2002-03-15
From Annie:
Joe used 1/3 cup of olive oil, which was 3/4 of the amount that he had. How much olive oil did he have!
Testing a hypothesis 2002-03-14
From A student:
A large distriutor of cosmetics has kept his outstanding accounts receivable to a mean age of 18 days over the past year. This average is considered a standard by which to measure the efficiency of the credit and collections department. Management wishes to check if receivables in the current month is over standard and will do this at a significance level of 0.50. A random sample of 100 accounts yields an average of 20 days with a standard deviation of 9 days. what should management conclude?
The square root of i 2002-03-14
From Arlene:
what is the square root of i, if i=x+yi?

what is the square root of 1-i? i'm getting problems like these in which I do not understand.

3 5/8 and 2 1/4 2002-03-13
From Shirley:
3 5/8 and 2 1/4 what is the percentage of 2 1/4 to 3 5/8.
15 miles at 13 miles per hour 2002-03-12
From Rich:
If I were traveling 15 miles at 13 miles per hour how long will it take?
My 1978 Chevy has a 350 cubic inch engine 2002-03-11
From Sharon:
If my 1978 Chevy has a 350 cubic inch engine, about what size engine would that be in liter?
x and y-intercepts 2002-03-10
From A student:
I have the problem- f(x)= X-5/X2+X-6 and I have to find the vertical asymtope, horizontal asymtope, x-intercept, and y-intercept. And graph the problem. I am having problems finding the y-intercept.
The best time to teach math 2002-03-10
From West:
My name is West. I teach 4th grade. I would like to know if there is any research which tells about the best time to teach math. Should it be taught in the a.m. or p.m.
Multiplying decimals 2002-03-10
From Kaitlin:
I just recently had a test on multiplying decimals and I did not do really well on it. Only 5 kids out of 19 got a passing grade. My teacher says that she will give us a different test and we can take it again, but I'm still not sure of it. My teacher has taught me a lot and she had done a wonderful job of it but I'm just confused with where to put the decimals and stuff like that. I have a math practice workbook that I do for fun and they have nothing on decimals in it. I have checked on websites to try to find worksheets but I really couldn't find a good one. Can you please help me either give me some tips or clues or send me a worksheet.
The isosceles triangle of smallest area 2002-03-08
From Lettie:
can you find the isosceles triangle of smallest area that circumscribes a circle of radius of one?
Percentage difference 2002-03-08
From Tedd:
Can you give me the formulas for calculating percentage differences between two numbers? For example: if the first number is 10 and the second number is 15, then the second number is 50% larger than the first number. However, the formula to calculate that percentage won't work if the first number is greater than the second number as in the following example: The first number is 15 and the second number is 10, with the second number being 33.3% less than the first number. Or maybe I'm mistaken and the same formula will work in both situations.
Factor completely 2002-03-07
From Taylor:
I'm supposed to completely factor this but I don't know what to do with all the variables.

a3b5 - a2b5 - 12ab5.

Does it have anything to do with b5 being a common factor or am I completely off?

A sequence 2002-03-07
From Caroline:
hi, here is the problem,

1
11
21
1211
111221
_ _ 2_ _ _

we can't get the sequence of the last line ,with the 3rd number being 2,thanks

The square root of 2 2002-03-05
From Roger:
Does two (2) have a square root or do the numbers just keep going? Are there any other numbers that behave like two when it comes to extracting the square root?
From Patrick:
The community of melfort is planning to build a circular wading pool in the park. The pool will cover an area of 1000m2. The building committee has decided to put a 5m cement pad around it. How much additional area will the cement pad take up?
The slope of a tangent line 2002-03-04
From Ridley:
Suppose a function f(x) has the line 3x+4y=2 as its tangent line at x=5. Find f'(5).
Percentage 2002-03-03
From Nathan:
I have two questions:
1. 25% of what number is 195?
2. 42 is what percent of 112?

Mixed numbers, whole numbers and improper fractions which are less than 2. 2002-03-03
From Dawn:
Change each mixed number to a whole number and an improper fraction which is less than 2. 3 1/2 = 2 /
What number am I? 2002-03-03
From Samantha:
I am an even number that has more ones than tens. My thousands digit is the quotient of 9 divided by 3 and my tens digit is the sum of 3 and 3. I have no hundreds. What number am I?......Please answer this for me...The answer I come up with is 3,060...Is this right?..
The median with ties 2002-02-27
From Marcel:
What, exactly, is the proper way to determine the median of a set of numbers when doubles or triples of a number are part of that set? Do the doubles count as two and the triples three, or does each count only as one toward determining the median.
Two circles inscribed in a rectangle 2002-02-27
From Amina:
Given a rectangle with dimensions L=6, H=5. Two circles are inscribed such that they touch each other(circles are adjacent to each other) and also their circumferences touch 2 sides of the rectangle. One of the circles has radius=4. Find the radius of the other circle.
Simplify this expression 2002-02-26
From Francine:
2X power 5 Y power 3 times 18 X power -5 Y power -3 divided by X power 1/3 Y power 1/4.

I came up with
`     36 ---------- X 1/3 Y 1/4 `
The book says 36 x1/3 y1/4.
I don't get it.

sin 2x = cos 3x 2002-02-25
From Allan:
solve:

sin 2x = cos 3x

Primary question: how do you handle the cos 3x?

Answered by Paul Betts and Chris Fisher.
The substitution method 2002-02-24
From Joe:
whats the answer to this question? 3x+y=11
x+2y=-3

its substitution method i am having alot of trouble figuring it out. send the answer as soon as possible. thank you

A hat of a different color 2002-02-24
From Kirstin:
A teacher made a deal with 3 of his students. He said that if you can guess what color hat you have on your head without looking, I will pass you. There were 2 red hats and 3 blue hats. The deal worked like this: The three students would close there eyes, and the teacher would put a hat on each of their heads and then hide the other 2. Then one at a time, the students would open their eyes and try to figure out what color hat was on their head. The student could guess or pass. This is what happened when they put their deal to the test: A boy named Arturo was first and opened his eyes but wasn't sure so he passed so he didn't get it wrong. Belicia was next and she passed too because she wasn't sure. Also she thought about the fact that Arturo didn't know. Carletta was last and without even opening her eyes, she knew for sure what color hat she was wearing and her answer was right. So i have to figure out what color hat she's wearing for sure.
350 students took the math A exam 2002-02-22
From Jim:
at a high school 350 students took the math A exam. 82% passed the test. 40 students that failed the exam in june, took the exam in August. 70% of this group passed the August test. How many of the original 350 students have passed the exam before september?
Answered by Paul Betts and Penny Nom.
1,4,27,____,_____46656 2002-02-21
From Brenda:
1,4,27,____,_____46656..... please find the fourth and fifth numbers in this sequence.
Alfredos house number 2002-02-21
From Aunt Patty:
Alfredos house number is between 20 and 35. The sum of the digits is less than 5. If you subtract 1 from it you would get a multiple of 3. If you add three, you get a multiple of 5. What is Alfredos house number.
Proof by induction 2002-02-20
From Tamaswati:
How do I prove the assertion that "the determinant of an upper triangular matrix is the product of the diagonal entries" by mathematical induction? (Before I check this assertion for a few values of n how do I rephrase the assertion slightly so that n appears explicitly in the assertion?)
An octagon-shaped deck 2002-02-20
From An instructor:
How can you solve for finding the side measurements of an octagon-shaped deck that is 10 feet long and 10 feet wide.
When will the calendar be the same as 2002? 2002-02-20
From John:
When will the calendar be the same as 2002? I know the answer is 2013, but I don't know how to answer this mathematically, or if it is possible to do so. This is a ninth grade level algebra question my daughter received from her teacher. Any ideas?
Answered by Chris Fisher, Patrick Maidorn and Penny Nom.
Shipping charges 2002-02-19
From Sohail:
A mail order company charges a fixed fee for shipping merchandise that weighs 1 pound or less, plus an additional fee for each pound over 1 pound. If there shipping charge for 5 pounds is \$4.80, and for 12 pounds is \$6.20, find the fixed fee and the additional fee.
A farmer takes 100 animals to the market to sell. 2002-02-19
From Ann:
A farmer takes 100 animals to the market to sell. All are sold and \$100 is earned. The prices were \$5.00 per cow, \$1.00 per sheep and \$.05 per pig. At least one of each kind of animal was sold. How many of each kind of animal did the farmer take to market?
Sampling distributions 2002-02-18
From A student:
1. given: n = 40, standard deviation is not known, population of individual observations not normal. does the central limit theorem apply in this case? why or why not?

2. for an estimation problem, list two ways of reducing the magnitude of sampling error?

3. What will happen to the magnitude of sampling error if the confidence level is raised all other things remaining the same? justify your answer?

Double square roots 2002-02-17
From Ali:
i have a question about how to do double square roots with variables and powers.

example : v/"" v/"" 81y8

A degree 5 polynomial 2002-02-17
From Carla:
Write an equation for a polynomial of degree 5 given the following zeros:
-7+3i, -2+sqrt(13), 6

Can the standard deviation ever = 0? 2002-02-16
From Karen:
If given a class of 30 people who take a test with a mean of 80. Can the standard deviation ever = 0? If so, why?
Diameter of a pipe 2002-02-16
From Landry:
I am trying to calculate the dia. of a pipe 60 inches long that will hold a gallon of water. What is the formula?
The perimeter of an ellipse 2002-02-14
From Harry:
I am planning to build a coffe table with an ellipse of 24x36 for the top. I wish to decorate the edge and need to know the lenght of the perimeter for lay out purposes. Is there an easy way to approximate this figure with out using intergal calculus?
Nets for pyramids 2002-02-14
From Michelle:
I want to have my students create nets for pyramids and I need to know how to find the correct range of degrees for the interior congruent angles of the isosceles triangular faces. For example, I know for a square-based pyramid that 77 degrees will work; however, I know other angle measures will also work. I'm just not sure how to find the minimum degree measure to have the net actually "work". I'm assuming the maximum would be 89 degrees, although that would make for a very tall pyramid.
36 is 20% less than _____? 2002-02-13
From Lori:
36 is 20% less than _____?
A man and his wife walk up a moving escalator 2002-02-13
From Monty:
A man and his wife walk up a moving escalator. The man walks twice as fast as his wife. When he arrives at the top, he has taken 28 steps. When she arrives at the top, she has taken 21 steps. How many steps are visible in the escalator at any one time.
Answered by Peeny Nom and Claude Tardif.
What is 20 to the thousandth power? 2002-02-12
From Kristi:
What is 20 to the thousandth power?
Three bugs on a line 2002-02-12
From Murray:
1. Three bugs are crawling on the coordinate plane. They move one at a time, and each bug will only crawl in a direction parallel to the line joining the other two.
• If the bugs start out at (0,0), (3,0), and (0,3), is it possible that after some time the first bug will end up back where it started, while the other two bugs switch places?
• Can the three bugs end up at (1,2), (2,5), and (-2,3)?

AND

2. A single peg is placed at the bottom left-hand corner of a grid that extends infinitely far up and to the right. You play a game in which you are allowed to make the following move: if the hole immediately above and the hole immediately to the right of a peg are both empty, you can remove the existing peg and place pegs in those two holes instead.
• Show that, no matter how you move, you can never remove all the pegs from the 3-by-3 square at the bottom left-hand corner of the grid. (b)
• Is it possible to remove all the pegs from the six holes closest to the bottom left-hand corner of the grid (the region indicated in the picture below)?

The slopes of the sides of the Great Pyramid 2002-02-09
From Christina:
The Great Pyramid is the largest of the Egyptian pryamids. When it was built, it was 481 feet tall and had a square base with 755-foot sides. The pyramid has two different slopes-one along its sides and the other along its edges. Which slope is steeper?
The number of hidden cubes 2002-02-05
From Katie:
This problem is about finding the number of cubes visible and hidden in a cube.

In a cube that is 3x3, 19 cubes can be seen. 8 are hidden.
In a cube that is 4x4, 37 cubes can be seen. 27 are hidden.
In a cube that is 5x5, 61 cubes can be seen. 64 are hidden.
In a cube that is 6x6, 91 cubes can be seen. 125 are hidden.

The question is:
Explain how you could find the number of small cubes that are visible and hidden in a cube of any size.

Answered by Paul Betts and Penny Nom.
Parabolas 2002-02-03
From Kuang:
-Who is credited for working with or studying the Parabola?

-What is a conic section?

-What does a parabola look like?

-How is a parabola formed?

-Where and how are parabolas used today in the real world?

Number conversions and averages 2002-02-03
From A student:
A table has the measurements of 1.6m by 2m, how much material is needed to cover table? I converted to cm then multiplied but got an answer of 32000cm ,so I divide by 100 to get to metres - the answer was 320 which I know is wrong - please explain!!

Also I need to explain in my own words what an 'average' is and I am struggling.

Square arrangements of clovers 2002-02-03
From Cassie:
Clyde had a strange fascination with numbers. One day he decided to mount his 4 leaf clover collection in groups of square numbers.he took a long piece of butcher paper and glue and began this arduous task.There was 1 clover,4 clovers.and then 9 clovers in the third set. what would be in the seventh set of 4 leaf clovers?
Zeta[2]=(Pi2)/6 2002-02-02
From alex:
Can you please tell me a proof that Zeta[2]=(Pi2)/6
I am a fraction 2002-02-01
From Anthony:
I am a fraction that is greater than 1 but less than 2. The sum of my numerator and denominator is 11. My denominator subtracted from my numerator is 1. What fraction am I?
The Euclidean Algorithm 2002-01-31
From Murray:
Can you please explain to me why the euclidean algorithm works?
Baseball and sit ups 2002-01-31
From A student:
A baseball team won 8 more games than it lost. If it played 56 games, how many games did it win?

On the first day of practice, Paul did 3 sit ups. On the second day he did 5, and on the the third day he did 8, and on the fourth day he did 12. If this pattern continued, how many sit-ups did ihe do on the sixth day of practice?

The size of a lot 2002-01-26
From Claudia:
I own a piece of property that I need to know the square feet for assessment purposes. The figure they came up with is wrong. They measured from one point to another and halved the sums but that means I own the cul de sac and we don't. My lot is 55 feet wide and one side is 108.96 feet and the other side is 146.04 that extends all the way to a circle. The front of the lot on the cul de sac is stated on the survey like this. 78.21 feet where R=40 feet. This large arc is taken off the size of our land. How many square feet is our lot.
Logico mathematical knowledge 2002-01-23
From A teacher:
How does young children's logico mathematical knowledge develop?
From Francine:

Hello, I've come up with an answer for the following problem but it's not the same as the book's answer. However, the book has a lot of mistakes in it and I don't know if I'm doing it properly or not. Your help would be soooo appreciated. It's driving me crazy.The problem is:

```
2             + 3          + 4
---------  +  ---------  +  ----------
(x-1)^3        (x-1)^2       (x-1)
```

[(x-1)^3 is (x-1) to power of 3 etc.]

Some trig problems 2002-01-22
From Grant:

Solve each problem for theta(there is no sign on my computer)for 0 is less than or equal to theta which is less less than 360

1. 2cosx-1=0
cosx=1/2
Anwser 60,300

2. tanx-2sinxtanx=0
tanx(-2sin+1)=0 (factor ?)
tanx=0 and sin= 1/2 (solve from there?)

3. 2sinx-cscx=0
2sinx-1/sinx=0
3sinx-1=0
3sinx=1/3(?)

4. 4cos(2x)+2cosx= -1
8cosx+2cosx+1=0
10cosx+1=0
10cosx= -1/10 (?)

5. cos(2x-30)=1/2
cos2x-cos30=1/2
cos2x-cos30-1/2=0
i don`t know what to do know

6. Sinx+cosx=0
Square both sides?

Miles and kilometers 2002-01-22
From Dennis:
I'm in the middle of purchasng a vehicle and it was built in Canada. Therefore it is in kilometers and not in miles. I forgot how many kilometers are in a mile. It registers as 183,049 kilometers.
Answered by Penny Nom and Judi McDonald.
Normal distribution 2002-01-21
From Danielle:
A teacher gave a test on which the students' marks were normally distributed, but the results were pathetic. The mean was 52% and the standart deviation was 12%. The teacher decided that the top 10% of the students should get A's, the next 20% should get B's, the next 40% should get C's, the next 20% should get D's, and the bottom 10% should get F's. To the nearest percent, what are the cutoff marks that will result in an A, B, C, D, and F?
Successive differences 2002-01-20
From Linsey:
what is the rule for working out the formula for a sequence with three lines of difference? eg.
```
1, 3, 7, 15, 29
1st line differences:  2, 4, 8, 14
2nd line differences:    2, 4, 6
3rd line differences:     2, 2 ```

Rolling 5 sevens before rolling a six or an eight 2002-01-20
From Tony:
When rolling 2 dice, what is the probability of rolling 5 sevens before rolling a six or an eight?
Answered by Andrei Volodin and Penny Nom.
The distance across a circle 2002-01-18
From Douglas:
If you know how far around a circle is (say earth) 25000 miles how do you calculate the distance across?
Making 24 2002-01-17
From Renee:
My 4th grade daughter and I need to find a simple math sentence using 5, 5, 3, & 7 to equal 24. You can add, subtract, divide or multiple.
A sale on eggs 2002-01-17
From A student:
A store had a sale on eggs, selling 13 eggs for the usual price of a dozen eggs. As a result, the price of the eggs was reduced by 4 cents a dozen. What is the original price for a dozen eggs?
My salary is doubled everyday for 30 days 2002-01-17
From Kanishk:
I recieve 1 penny the 1st day, 2 pennies the 2nd day, and my salary is doubled everyday for 30 days. How much money will I have by the end of the 30 day time period? (Is there a way of solving this problem without a chart?)
A sequence 2002-01-16
From Chris:
I have spent two days trying to determine the pattern to the following set of numbers: 1,4,9,1,6,2,5,3,6,4,9,6,4,8,1,____. I need the next four numbers to the sequence.
Children and probability 2002-01-16
From Bill:
If a family has four children, what is the probability that all 4 are the same sex?
Negative exponents 2002-01-16
From Julie:
If z to the power of -4= 1/z4 then how would you solve 1/t-2?
Linear regression 2002-01-16
From Murray:
If you have a set of coordinates (x[1],y[1]),(x[2],y[2]),...,(x[n],y[n]),find the value of m and b for which SIGMA[from 1 to m=n]AbsoluteValue(y[m]-m*x[m]-b) is at its absolute minimum.
50% 2002-01-15
From Lakarrieh:
4 is 50% of what number?
What is a group of three numbers called in a large number? 2002-01-15
From Laurie:
What is a group of three numbers called in a large number?

My son has this question on his 4th grade worksheet. I've taught middle school math for 7 years and nver heard of it.

8% tax 2002-01-15
From A student:
total price including tax is \$13359.60
8% tax was paid
What is the dollar amount of tax paid?

Algebra review questions 2002-01-14
From A student:
1. A wildebeast was observed racing a distance of 86.4m in 4.8 seconds. Find the speed of the wildebeast in m/s.

2. 8x - 7 - 5x = 23

3. 7 z - 3 (z + 2) = 26

From Lena:
how do you add vectors together?
If you are given the length and angles of both vectors and are asked to add/subtract them, how do you do it? I know you are supposed to do the head to tail method, but whenever i try it i get the wrong answer. I need help setting it up.

example: A is 2.7cm, and 60 degrees, B is 1.6cm and 135 degrees, find the magnitude and amplitude

The tangent function 2002-01-12
From Justine:
if you know that sin45degress = cos45degrees, how do you know that tan45degrees = 1?
The famous "train problem" 2002-01-12
From Karen:
How do you solve the famous "train problem"? For example, 2 trains leave different stations at the same time. One is traveling at 50 mph and the other at 40 mph. How long does it take them to meet?
Papy's Computer 2002-01-11
From Mary-Anne:
My second-grade son brought home a fun math worksheet which involved calculating sums using "Papy's Computer." I had never heard of this before and found it to be quite interesting. Each digit in a decimal number is represented by a 2x2 grid. Each grid square corresponds to one of the numbers 1,2,4, or 8.
Why do integers have the symbol of Z? 2002-01-11
From Stephanie:
Why do integers have the symbol of Z? Natural numbers have the symbol of N, whole numbers have the symbol of W. Our professor has asked us to find out why the letter Z is represented for integers.
A sequence of number pairs 2002-01-10
From Terry:
Three is the first number of a pair, and 8 is the second.

a. If 50 is the first number, what is the second number?
b. If 200 is the first number, what is the second number?
c. If 89 is the second number, what is the first number?
d. If a number n is the first number, what is the second number?

3-8
4-11
5-14
6-17
____
____
____
10-29
____
____
____

Glasses of wine 2002-01-10
From A student:

6 glasses of regular wine (12% alcohol) would equal aprox.? glasses of wine (8% alcohol)

a)9.33
b)8.5
c)7.75
d)9.0

A simplification problem 2002-01-10
From A Parent:
FIND

(A / B) . (C / D)
where
A = Y squared + 3 . Y cubed
B = Y squared + 4
C = 2 . Y + Y squared
D = Y + 4 Y squared + 3 Y cubed

An octagon inscribed in a circle 2002-01-10
From Kent:
A circle of 30 in. diameter has an octagon (8 equal chords) inscribed in it. What is the length of each chord?
Nickles, dimes, quarters and fifty cent pieces 2002-01-08
From A parent:
The total for all coins counted is \$4,564.50 The last coin added to the pile is a 50 cent piece There are 8 times as many 50 cent pieces as there are quarters There are 6 times as many dimes as nickles How many of each are there?
All of the Christmas trees are fifty-five percent off. 2002-01-08
From A teacher:
All of the Christmas trees are fifty-five percent off. Madison bought a tree and paid \$103.50. Assuming no tax, what was the original price of the tree?
Maple trees and pine trees 2002-01-06
From A student:
A team of scientists found that in a forest there was four maple trees for every nine pine trees.How many maple were there if they counted 45 more pine than maples?
Catenary 2002-01-02
From Jason:
I am a high school math teacher. I was asked by a friend who is in architectural design for a method for determining the volume of what he called a Catenary.

The Catenary curve is modeled by the equation y=a cosh(x/a). I ran into a mess when I tried to compute the volume of the solid formed by revolving that curve around the y-axis.

Isoperimetric quotients 2002-01-02
From A student:
I'm stuck on my GCSE Maths coursework, what do isoperimetric quotients measure?
2/3 vs 3/4 2002-01-02
From Julia:
So, here's my question. Some of the problems they've had to do starts off with two fractions, and they have to tell whether the two fractions are:
1. The first one is greater than the second one
2. The first one is less than the second one, or
3. They are equal.

One day my son had the problem of 2/3 vs 3/4. Without drawing out a pie chart, how in the world can a child "eyeball" a problem like this and tell what the correct answer is? I've also tried to teach about making common denominators, but that's going over his head at this point.

Answered by Denis Hanson and Harley Weston.
Fractions to decimals and percents 2001-12-31
From A student:
2/5 , 4/8 , 4/10 , 3/5 , 6/8 , 7/7 (what is the decimal and percent for each)

1/5 , 1/10 , 1/8 , 1/1 (what is the decimal for each)

100 PERCENT, WHAT IS THE DECIMAL?

The ratio of boys to girls in a class is 1:4. What percent of the class are girls?