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326 items are filed under this topic.
Lot size / acreage (more than three sides) 2007-05-11
From Martha:
What is the lot size of the following dimensions equivalent to acre. 141.85 x 52.55 x 217.63 x 38.89 x 68.08
Answered by Penny Nom and Stephen La Rocque.
Calculating volume of concrete, dirt, sand, anything. 2006-11-17
From Debbie:
[This article contains a special calculator to help you find the volume (for example, the cubic yards) of material required to fill (or empty) a space if you know the length, width and depth.]
We are wanting to pour a 24'x30' slab that is 5" deep. How many cubic yards of cement do we need?

Answered by Penny Nom.
A rectangle and a circle 2017-08-12
From Ramzan:
a diagram shows the shape of rectangular framework with length (2x+20)cm and with (y+10)cm . The outline is made of wire . If a circle with diameter 56 cm is to be made from the wire and the area of the rectangle is 420 square centimeter ,find the possible lengths and width of the rectangle
Answered by Penny Nom.
Ratios and proportions 2017-08-01
From khurram:
what is ratio and proportion? please give a detailed note on this topic, i am really panic of these calculations
Answered by Penny Nom.
Squares and rectangles 2017-07-15
From Tront:
So, there's a general rule that all squares are rectangles but not all rectangles are squares. Im trying to find a term that would describe this relationship. I've found that if all of A is B but not all B is A then I'd say that A is a subset of B, but is there a term that describes the relationship as a whole? I don't want to describe the components, I want to describe the relationship as a whole.
Answered by Penny Nom.
Of cows and men 2017-07-04
From Akash:
In a group of cows and man the number of legs is 32 more than the twice the number of heads.The number of cows is?
Answered by Penny Nom.
Long division with decimals 2017-06-16
From Kenneth:

Why is it recommended to move the decimal from a divisor when dividing so that the divisor is a whole number? I know how to divide by moving the decimal from the divisor, but I cannot explain the reason.

I thank you for your reply.

Answered by Penny Nom.
1 acre as a 2 foot wide strip of land 2017-04-25
From alan:
How can one convert 2 acres (a square - area) of land into a strip of land that is 2 feet wide and (?) feet long?
Answered by Penny Nom.
Rational numbers between -2 and -3 2017-04-08
From Medha:
Find 12 rational numbers between-2 and -3
Answered by Penny Nom.
The sum and difference of two numbers 2017-03-20
From Olivia:
The sum of two numbers is 87 and their difference is 29. What are the two numbers
Answered by Penny Nom.
Tons of sand 2017-03-01
From Elizabeth:
Hello my arena is 132.23 feet width by 132.23 feet length. I need to put 4 inches of sand. How many tons of sand do I need ?
Answered by Penny Nom.
Divisibility of 3n^5+7n 2016-12-14
From Parag:

Question from Parag, a student:

if n is a natural number,then 3n^5+7n is divisible by

i got the answer but still i need a valid alternate approach.

Answered by Penny Nom.
Profit and loss on two shirts 2016-12-06
From Mahesh:
A man purchases one shirt and one T-Shirt for Rs. 6000. He sells the shirt at a profit of 20% and T-Shirt at a loss of 10%, as a result he gains 2% on whole transaction. what is the cost price of the T-Shirt ?
Answered by Penny Nom.
Gallons and cubic inches 2016-12-05
From Theresa:
If I did not know the cubic inches in a liquid gallon how would I find it? In other words what is the formula for this?
Answered by Penny Nom.
Standard form 2016-09-22
From anna:
ok. i have b=2/3x+5/7. im supposed to change it to standard form. how do i do that?
Answered by Penny Nom.
The modulus of a complex number 2016-07-29
From Cheyenne:
There's a question on my Summer Assignment I cant figure out. Here it is:

Find the absolute Value of the complex number. -5i

Please help?

Answered by Penny Nom.
The perimeter and area of a shape 2016-06-30
From Scott:
If I have a 16 x 32 rectangle the square feet is 512. So if I take a rope 96 feet long , which is the lineal feet of the rectangle, and manipulate it to any shape I want does the square footage inside the rope stay at 512 square feet? Thanks in advance!
Answered by Penny Nom.
15.86 acres 2016-04-21
From Ronald:
If a rectangular piece of land is 1320 ft. on one side, how many feet would be required on the other side to equal 15.86 acres?
Answered by Penny Nom.
The area and the perimeter of a rectangle 2016-04-12
From kimberly:
is there a relationship between the are and the perimeter of a rectangle? explain.
Answered by Penny Nom.
The area of a circle and a square 2016-04-10
From Richard:
I cannot understand why if you have a perimeter say of 4 units as the circumference of a circle then you reshape it into a square you lose very approximately some 20% of its volume but the perimeter length stays the same.
Can you please explain this to me as to why the volume decreases.

Answered by Penny Nom.
Setting up a pool 2016-04-09
From BETH:
i am trying to cover an area for a 15x15 foot round pool with play sand before I set up the pool. My playsand bag is 50 lbs , says it covers .5 cubic feet per bag. How many bags do I need?
Answered by Penny Nom.
20 mangoes 2016-04-01
From Mussharat:
I have 20 mangoes and have to put them in 5 boxes such that the numbers will be odd numbers.Also I can't cut or take the seed out from the mango . What should I do. It's really confusing.
I'll be more than happy if you could help me.

Answered by Penny Nom.
A block wall 2016-03-15
From Robert:
I have a wall 40 ft. long and 4 ft. tall as well as another one that is 30 ft by 3.5 ft. tall that I am trying to build. how many 6 inch by 12 inch landscaping blocks do I need?
Answered by Penny Nom.
Can you construct a regular 21-gon? 2016-03-08
From Peter:
hi, i know that if i use a compass to draw a circle, i can use the same setting to mark 6 intervals along the circle circumference, how would i go about marking out 21 equally spaced points around the circumference?

if there an online calculator i can us, or some other interesting trick?



Answered by Robert Dawson.
Complex numbers in standard form 2016-01-15
From Michael:
express the following complex numbers in standard form (2+3i)+(5-2i)
Answered by Penny Nom.
Division and units 2015-09-08
From Kenneth:

Would there be a reason to divide a number without units by another number with units? Here is an example:

35 divided by $5.00 or 35/$5.00

The answer cannot have units ($) because $5 X 7 does not equal 35 but instead $35.00.

$35.00 divided by 5 or ($35.00/5) and $35 divided by $5.00 or ($35.00/$5.00) make more sense.

I thank you for your reply.

Answered by Robert Dawson.
The diameter and circumference of a circle 2015-09-01
From Tracey:
I own a custom workroom, I am figuring out fabric quantities or an estimate. When at the job site, I forgot to measure the diameter of the semi circle shape that I have to make a cushion for!!!
If the circumference of the semi circle is 165" what would the diameter be, maybe half this measurement????

I appreciate any help...I basically need the width from left to right to see if I can fit the cushion on one width of fabric that is 52" wide!

Answered by Penny Nom.
Why is the area of square not conserved when it changes to a rhombus? 2015-06-28
From shubham:
Why is the area of square not conserved when it changes to a rhombus, both have equal sides still rhombus have less area than square.??
Answered by Penny Nom.
The intersection of a plane and a cone 2015-05-16
From Tom:
Is there a way to derive an equation that describes the perimeter of the intersection of a plane and a cone regardless of the angle of the plane to the cone. Assume that the plane does not cut through the base of the cone, the x, y, z location of the vertex is known, the distance from the vertex to the plane through the axis is know., and that the angle of the cone is known.
Answered by Chris Fisher.
Expand and Simplify (3x+5)(5x-9) 2015-04-23
From chloe:
Expand and Simplify (3x+5)(5x-9)
Answered by Penny Nom.
n^2 is a multiple of 100 2015-03-30
From Rahul:
I have to prove that n^2 is a multiple of 100 is necessary or Sufficient condition (or both) for n being multiple of 10
Answered by Penny Nom.
A cone is 2/3 full of sand 2014-12-14
From Janice:
A cone with a radius of 3.5 cm and a height of 12 cm is 2/3 full of sand.
What is the volume of the sand inside?

Answered by Penny Nom.
Shaking hands at a party 2014-12-03
From Nazrul:
At a party, everyone shook hands with everybody else. There were 66 handshakes. How many people were at the party?
Please help me.

Answered by Penny Nom.
The density of sea sand 2014-11-02
From Lenny:
Hi There,

I need to find out the the density of sea sand to convert one metric ton to cubic meter as I am submitting for a tender which is in cubic meter but the requirement is in metric ton. I searched through the web site but no density of sea sand is given though there is specific Gravity of dry sand is available. I was given a density of 1.6 to work with. If that is true am I right to say that 1 cubic meter of sea sand is equivalent to 1.6 metric ton? Please help as I am getting confused with what I am able to find out on the web.
Thanks much in advance

Answered by Penny Nom.
4 card hands 2014-11-02
From Ronaldo:
How many Mus hands (combination of 4 cards allowing repetitions) can be made from a deck containing 8 types of cards?

RRSS, RRS7, etc.

I think 330. If so, what is the formula?

Answered by Penny Nom.
A 10-foot piece of PVC pipe 2014-10-21
From David:
A plumber has a 10-foot piece of PVC pipe. How many 9/5-foot pieces can be cut from the 10-foot piece ?
Answered by Penny Nom.
A fact family containing 4, 4 and 16 2014-10-14
From Leslie:
I am helping my son and the question is 4,4,16 in fact family what does that mean
Answered by Penny Nom.
The perimeter of a parcel of land 2014-09-18
From Shirley:
What is the perimeter of a parcel of land that is 564 acres square
Answered by Penny Nom.
Expand and simplify [x-3][x+3] 2014-07-16
From symion:
Expand and simplify [x-3][x+3]
Answered by Penny Nom.
The number of standard deviations 2014-06-15
From Dawn:
Suppose that, at a certain college, the average weight of all male students is 160 pounds with a standard deviation of 30 pounds. A certain male student weighs 145 pounds. Determine how many SD's his weight is above or below average.
Answered by Penny Nom.
Bags of sand 2014-06-06
From Robert:
We have a section that is 20ft long by 14ft wide and 4inches deep, the bags of sand are .5 cubic ft. How many bags of sand do we need to fill this space evenly.
Answered by Penny Nom.
A circle a square and a rectngle 2014-05-12
From mazhar:
suppose the length and breadth of the rectangle are 5 cm and 10 cm respectively and M is a point along the corner of the circle. what is the radius of the circle?(diagram is given..but i didn't mention it..actually the diagram looks like a circle inscribed in a square and the right bottom corner one rectangle will be given ,it is touches to circle at a point M that I've already mentioned and the dimensions of that rectangle also I've mentioned) please help me out..
Answered by Penny Nom.
2 rectangular prisms are similar by a scale of 0.75 2014-03-16
From gina:
2 rectangular prisms are similar by a scale of 0.75. The volume of the smaller prism is 27cm3 (cubed). How many cubic centimeters is the volume of the larger prism?
Answered by Penny Nom.
A box-and-whisker plot with one whisker 2014-01-09
From Susan:

Question from Susan, a teacher:

I read your answer to the question about could a box & whisker have NO whiskers.
It made sense to me. However I am preparing for my advanced class and I have a sample graph comparing box plots of data.
Several of the box have only 1 whisker. There is no explanation for this. Can you help me out. I cannot think of a data set that would produce this. Thanks!

Answered by Penny Nom.
Fractions and square roots 2013-12-04
From arionne:
How do you solve a square root with improper fractions like 121 over 49
Answered by Penny Nom.
A stem and leaf plot 2013-10-24
From mary:
I'm trying to answer my child's question on stem and leaf plot. For grade 4, the question is where do you put 57 in this list

6    0
5    4 8 8 9 4 6 4

Answered by Penny Nom.
Proportional rates 2013-10-10
From Varsha:
A province's Ministry of Social services has found that both the number of people needing social assistance and the province's total expenditures on social assistance are proportional to the rate of unemployment. Last August when the provincial unemployment rate was 8.4 %, the province provided assistance to 89,300 individuals at a total cost of 4107.4 million. The forecast unemployment rate for next August is 7.9%. How many people can the province expect to need social assistance next August? What amount should the province budget for social assistance in August?
Answered by Penny Nom.
Equal ordinate and abscissa 2013-08-15
From sonit:
the slope of tangent to the curve y=(4-x^2)^1/2 at the point, where the ordinate and abscissa are equal, is
Answered by Penny Nom.
A mixture problem 2013-07-29
From Lucy:
Hi, For the following question:

Ten pounds of mixed nuts contain 50 percent peanuts. How many pounds of peanuts must be added so that the final mixture has 60 percent peanuts?(A) 2.5 (B) 5 (C) 6 (D) 10 (E) 12.5,

my math book gives my the following explanation: Try choice (C): 6 pounds of peanuts. The original 10-pound mixture contained 50 percent peanuts, or 5 pounds. Now you have 11 pounds of peanuts in a 16-pound mixture, more than 60 percent. This result automatically eliminates choices (D) and (E) as well.Why would this result automatically rule out D and E? How can you tell? Thank you for taking the time to answer my question.

Answered by Robert Dawson and Penny Nom.
A 3 acre plot 2013-06-17
From Chad:
I have 3 acres 100ft at the top and bottom what is the length of each side to make up the 3 acres
Answered by Penny Nom.
4 linear equations with 3 unknowns 2013-04-12
From Marian:
how to solve for 3 unknowns in 4 simultaneous equations
Answered by Penny Nom.
The dimensions of a rectangle are in the ratio 5:3 2013-03-08
From SM:
4. The dimensions of a rectangle are in the ratio 5:3. If the longer side is 18 cm,

a) What is the length of the shorter side?

b) What is the area of the rectangle?

Answered by Penny Nom.
100 animals 2013-02-25
From Jessica:
You have exactly $100.00 to spend. You must get 100 animals.
The chicks cost $0.10 each.
The pigs cost $2.00 each.
The sheep cost $5.00 each.
You must get some of each animal.
How many of each animal can you get?

Answered by Penny Nom.
A 2 acre plot 2012-10-22
From bob:
If a plot of land on the south side is 290.16 feet wide, how many feet on the west and east side to the north to make a 2 acre plot?
Thank You Bob

Answered by Penny Nom.
GST in New Zealand 2012-10-10
From Colleen:
I work out my claimable gst each month but need to know the total sales or purchases amounts for filling in my six monthly paper work. How do I do that. I tried doing the opposite of calculating the gst i.e. x3 and /23 but it is slightly different to my total.
Answered by Penny Nom.
Guess and Check 2012-09-24
From Myron:
My daughter has homework involving Guess and Check. Her Math book is no help with the question in her homework so hopefully you can help me. Here's the question: "The sum of a number and it's double is 24. Use the Guess and Check method to find the answer". Help!!
Answered by Robert Dawson.
How high must the trailer be filled with sand? 2012-08-06
From Deb:
Your customer has ordered 67 cubic yards of sand. The inside dimensions of your trailer are 40 feet long by 7 feet wide by 9 feet high. How high must the trailer be filled with sand? (Round up to the nearest inch.)
Answered by Penny Nom.
A sand box with 14 sides 2012-07-10
From Tom:
Want to build a sand box for a pool that is fourteen foot round wanted to make it in fourteen pieces of wood what angle would each piece be and how long would each piece be
Answered by Harley Weston.
An octagonal sandbox around a pool 2012-06-12
From Linda:
My pool is 15 feet across and it is round.

How do I measure to cut wood to build a sandbox around it? was thinking it will look like an octagon.


Answered by Harley Weston.
Expanded exponential form? 2012-06-12
From Ramon:
express the numbers 990 614 000 005 in expanded exponential form.
Answered by Harley Weston.
Multiplying binomials 2012-05-14
From Jordan:
How do I solve the equation:

Answered by Penny Nom.
Gravel, sand, cement and an equilateral triangle 2012-03-21
From saheed:
how many tonnes of gravel and sand,bags of cements will be required to concrete 5feet depth/deep of 4feet equilateral triangle?
Answered by Harley Weston.
Buying school supplies 2012-03-09
From Jada:
Hi, my daughter is having difficulties with a problem she is in the 5th grade, and insisted that it was a guess and check problem, but she really doesn't understand, and I don't either. Can you help us out?

Danielle is buying school supplies. She has $7.25 to spend.
Notebook: $0.75
Pencils: $1.95
Pens: $2.50
Planner: $5.00
Please help by explaining the guess and check strategy for a problem like this. Thank you.

Answered by Penny Nom.
Limits and composition 2011-12-30
From Rahul:
I want to know about limit proofs of composite functions. Like limit of log of a function equals log of limit of the function
Answered by Penny Nom.
Expanded form 2011-10-12
From Chris:
Write this number in expanded form
4 326 180 501


Answered by Penny Nom.
An exclusion zone around a triangle II 2011-05-03
From Aishwarya:
A long time ago Mr gibson found an island shaped as a triangle with three straight shores of length 3km, 4km and 5km. He declared an exclusion zone around his island and forbade anyone to come within 1km of his shore. What was the area of his exclusion zone? This question was answered but did not understand the explanation.
Answered by Robert Dawson.
Sample Standard deviation 2011-03-16
From Iris:
Help please: me on this type of math problem I can get through step one after that I get lost. Maybe you can explain it to me in a easier way to get the correct results. I have read the examples, but I am still lost cannot move on until the next practice until I get this one

Sample standard deviation
The following are distances (in miles) traveled to the workplace by employees of a certain computer company.

15,29,32 28 18 28
Find the standard deviation of this sample of distances. Round your answer to at least two decimal places.

Answered by Penny Nom.
The equation of a circle 2011-02-14
From Cristela:
find the equation and all the information in General Form and Standard Form of the Circle that will passed trough the point (2,3) (6,1) (4,-3)
Answered by Stephen La Rocque.
Multiplication and order 2011-01-21
From Janet:
Answered by Robert Dawson.
Four digits are to be randomly selected 2011-01-20
From sarahbear:
Suppose four digits are to be randomly selected (repetitions allowed) Find the probability that
A. 5562 is selected
B.0000 is selected
C. All four digits are the same
D. 2 is the first digit selected

Answered by Penny Nom.
Mathematics and a musical dilemma 2011-01-19
From rahul:
how is mathematics applied in entertainment?
Answered by Harley Weston.
A binomial random variable 2010-11-29
From yvette:
a binomial random variable has a mean equal to 200 and standard deviation of 10. find the values of n and p.
Answered by Penny Nom.
Mathematics and medicine 2010-10-13
From Dixie:
need equations used in medicine for medicine and intravenous administration
Answered by Penny Nom.
Thickness of sand 2010-07-07
In an 18 x 33 ft area how much is 4 yards of sand in inches to cover this area.
Answered by Penny Nom.
A collection of baseball cards 2010-07-01
From Martha:
Cody has a collection of baseball cards. Is it possible for him to place the cards into 5 boxes so that exactly 3 of the boxes contain an odd number of cards and the total number of cards in two of the boxes is the same as the total number in the other 3 boxes? Explain.
Answered by Robert Dawson, Penny Nom and Claude Tardif.
Expand and simplify 2010-06-15
From Alaa:
Expand and simplify

Answered by Penny Nom.
Roosters, hens and chicks 2010-06-10
From Kamarah:
If a rooster is worth 5 coins and a hen is worth 3 coins and chicks 3 together are worth 1 coin, how many roosters, hen and chicks totaling 100 can be bought with 100 coins?

you must buy at least one of each type of fowl
no fractional fowl
chicks are purchased in multiple of 3
find 3 solutions

Answered by Penny Nom.
Standard Deviation from a Proportion 2010-06-08
From silvestre:
A large company finds that approximately 17% of all purchases are returned for credit. If the company sells 100,000 different items this year, about how many items will be returned. Find the Standard Deviation.
Answered by Janice Cotcher.
Percentage increase 2010-05-20
From Rebecca:
Question from Rebecca:

In 2008 my land was valued at $84,000. In 2009 my land was re-valued at $235,000.00. What is the percent increase between the two values? I want to be able to express "the value was increased by x%."

Answered by Harley Weston.
Sand falling off a conveyer 2010-04-02
From Katherine:
sand is falling off a conveyer onto a pile at the rate of 1.5 cubic feet per minute. The diameter of the base is approximately twice the altitude. At what rate is the height of the pile changing when it is 10 feet high?
Answered by Penny Nom.
How many 5 card hands in a deck of 52 have 2 aces and 3 other cards? 2010-03-23
From Travis:
How many 5 card hands in a deck of 52 have 2 aces and 3 other cards?
Answered by Penny Nom.
The distance travelled by a minute hand 2010-03-06
From Patric:
How much distance will the minutes hand of length 14mm of a clock cover in moving from 5 to 10?
Answered by Penny Nom.
Standard form 2010-03-05
From Laura:
How do I change 3y=4x+1 into standard Ax+By=C standard form. This is my son's schoolwork. I homeschool him. I got the answer to the problem as 3y=4x+1, but it needs to be written in standard form and I know it needs to read 4x-3y=-1, but how do I get that answer into standard form. I need to know how to explain it to him. Can you show me? Thank you so much.
Answered by Penny Nom.
2+3 =10 and 7+2=63 and ... 2010-03-01
From brenda:
if 2+3 =10 and 7+2=63 and 6+5 =66 and 8 +4 = 96 then 9+7+ ??????
its driving me crazy !!

Answered by Penny Nom, Claude tardif and Melanie Tyrer.
Birds and cats 2010-02-13
From Sophia:
While visiting a pet store, you notice that there are only birds and cats in the cages. You can't help but wonder how many of each animal there is in the yard. But when you ask the store manager how many of each animal he has, he refuses to give a direct answer. He says there are 16 animal heads and 42 animal feet. How many birds and cats are there in the pet store? It said to show all your work. Explain in words how you found your answer. Tell why you took the steps you did to solve the problem.
Answered by Penny Nom.
A snail on an elastic band 2010-02-03
From Joe:
A snail starts crawling from one end along a uniformly stretched elastic band. It crawls at a rate of 1 foot per minute. The band is initially 10 feet long and is instantaneously and uniformly stretched an additional 10 feet at the end of each minute. The snail maintains his grip on the band during the instant of each stretch. At what points in time is the snail
(a) closest to the far end of the band, and
(b) farthest from the far end of the band?

Answered by Robert Dawson.
A pile of sand 2009-12-16
From Malik:
Sand is leaking out of a hole at the bottom of a container at a rate of 90cm3/min. As it leaks out, it forms a pile in the shape of a right circular cone whose base is 30cm below the bottom of the container. The base radius is increasing at a rate of 6mm/min. If, at the instant that 600cm3 have leaked out, the radius is 12cm, find the amount of leakage when the pile touches the bottom of the container.
Answered by Harley Weston.
Three numbers that have the sum of 45 2009-12-04
From amanda:
there are three numbers that have the sum of 45.The greatest of the three numbers is 2 greater than the least number.What are the numbers?what is the formula to get the answer?
Answered by Penny Nom.
Two movies in one day 2009-11-18
From jazzy:
ann and tim saw two movies in one day.The two movies lasted 4hours long .One movie was an half hour longer than the other .How many hours did the shorter movie run
Answered by Penny Nom.
A minute hand 2009-11-05
From Pardha:
A minute hand of table clock is 3cms long. How far its tip move in 20 minutes
Answered by Penny Nom.
Guess and check 2009-11-01
From Laura:
There is a game at the fair in which you toss balls into bowls to win fish. There are 52 bowls. The larger bows contain five fish, and the smaller ones contain three fish. If there are 202 fish total, how many bowls of each size are there?


Answered by Penny Nom.
Standard deviation 2009-10-27
From Reggie:
After you have computed the standard deviation of a set of 40 scores, you discover that the lowest score is in error and should be even lower. Will correcting this error affect the standard deviation?
Answered by Penny Nom.
Guess and check 2009-10-27
From Eileen:
Caslin has a total of 50 red beans and green beans. If she trades 1 red bean for 4 green beans, she will have 113 green beans, how may red beans and green beans does she have?
Answered by Penny Nom.
Sarim has $1 in coins. 2009-10-27
From Elizabeth:
Here is the question asked: Sarim has $1 in coins. One-fifth of the coins are dimes, two-fifteenths are nickels, and two-thirds are pennies. Tell how many of each coin he has. I am not sure how to start this problem.
Answered by Penny Nom.
Chickens and pigs 2009-08-28
From David:
A farmer has a number of chickens and pigs. There are 24 heads and 80 ft. How many pigs and how many chickens are there?
Answered by Robert Dawson.
A degreaser for a fish tank 2009-07-23
From charlie:
I have a tank that is 10 feet in diameter that I want to put floating degreaser in.The rate for the degreaser is 1/2 gallon per square foot of surface water.How do I figure out how many gallons I need?
Answered by Penny Nom.
Is one Infinity larger than another in the extended real number system? 2009-06-24
From Justin:
Hello there, I was wondering if one infinity is larger than another in the extended real number system (just like in the transfinite ordinals and cardinals with respect to infinite sets) or are all infinities the same size in the extended real number system? Thanks sooo much for answering my question! I greatly appreciate it!

All the Best,


Answered by Robert Dawson.
The center of an ellipse 2009-04-21
From Nae:
what is the ellipse center of 5x^2+3y^2=15
Answered by Stephen La Rocque.
A perpendicular line in standard form 2009-04-21
From Kristy:
Can you help me with this equation? Find the equation, in standard form of the line perpendicular to 2x-3y=-5 and passing through (3,-2) With the equation in standard form with all integer coefficient.
Answered by Stephen La Rocque.
How many handshakes took place? 2009-04-15
From wm:
Suppose every member of the House of Representatives shakes hands with every other member exactly once. How many handshakes took place ?
Answered by Penny Nom.
Z-score 2009-03-25
From Barb:
I am having trouble finding information on a z score and the conversion to the number of standard deviations a z value can be away from the mean. What exactly does that mean and what am I looking for? Help Please.
Answered by Harley Weston.
Conversion factor 2009-03-23
From kab:
Would like to photocopy a Landscape Design. What is the Conversion Ratio or magnification required to convert 1" = 10 feet to 1/4" = 1 foot?
Answered by Harley Weston.
License plates and poker hands 2009-03-14
From CC:
You have a license plate it can have 6 numbers/letters you can use the numerals 0-9 and the letters A-Z how many combos are possible and how did you figure it out?

Question 2,

Your dealt an Omaha hand You have KKKQQ, how many different hands can consist of the same cards.

Answered by Harley Weston.
The sum is 43 and the difference is 9 2009-03-02
From Teresa:
Hi, My 10yo son came home with this two problems and we can't figure out how to solve them.

1. Find two numbers whose sum is 43 and whose difference is 9 and
2. Find two numbers whose sum is 25 and whose difference is 11..
Many thanks

Answered by Robert Dawson, Stephen La Rocque and Harley Weston.
An octagonal landscaping frame 2009-03-01
From Richard:
Hi I am trying to put landscape timbers down in octagon shape that measures 6 feet across and outside measures 360 degrees.. The timbers are 4 inches by 4 inches. I need to know at what angle to cut boards and at what length i need to complete octagon.
Thanking you in advance for your kind assistance.
Richard :)

Answered by Harley Weston.
wo consecutive numbers with a product of 9506 2009-02-25
From sofie:
find two consecutive numbers with a product of 9506
Answered by Penny Nom.
Nullity 2009-02-16
From Justin:
What exactly does the term nullity mean in the context of transreal numbers invented by Dr. James Anderson?

Thanks for your help in answering this question!

All the Best,


Answered by Robert Dawson.
Randy' age and Mandy's age 2009-02-03
From carolina:
Randy is 4 times as old as Mandy, in 12 years, Mandies age is half of Randy's . how old is each now?
Answered by Penny Nom.
The amount of concrete in a football stand 2009-01-30
From jacques:
A football stand 150 yd long has 20 tiers of seats; each tier has a rise of 2ft and tread of 3ft.Its construction of reinforced concrete with a cross section as shown. Find the amount of the material used in its construction.
Answered by Penny Nom.
A seven card poker hand 2009-01-12
From Sean:
from a standard card deck, seven cards are chosen at random. find the probability that the set chosen contains exactly three of each of two different face values.

the second part of the problem asks the probability that the card hand contains exactly three 2's and exactly three 5's.

Answered by Robert Dawson.
An area of 64cm squared and a perimeter of 64 cm. 2009-01-07
From Dale:
i need to draw an object that has an area of 64cm squared and a perimeter of 64 cm. Can you help me out......
Answered by Robert Dawson.
Two numbers 2008-12-15
From HERB:
I am thinking of two whole numbers. When I add them , their sum is 123. When I subtract the lesser number from the greater number their difference is 45. What are my numbers?
Answered by Penny Nom.
How many four-legged animals are in the field? 2008-12-02
From evelyn:
Some chickens, cows and sheep are in the field. Their number of legs is 12 more than twice their number of heads. How many four-legged animals are in the field?
Answered by Harley Weston.
Sigma in a normal distribution 2008-11-18
From Justin:
Suppose the random variable Y can be described by a normal curve with Mu=40. For what value of the standard deviation is P(20 less than or equal to Y less than or equal to 60) = 0.50


Answered by Harley Weston.
An algebraic exercise with fractions and radicals 2008-11-18
From Rubén:
Question from Rubén, a teacher:

I have the ecuation:

U = [yb / (ab+a^2)]^1/2 + [ya / (ab+b^2)]^1/2

I know for sure this reduces to

U = [y (1/a + 1/b)]^1/2

but I cannot find a way to get into that result!


Answered by Rubén Osuna.
How do I compare fractions and decimals? 2008-11-18
From Alexis:
How do I compare fractions and decimals ?
Answered by Penny Nom.
The product of two numbers is 2400 2008-10-16
From belinda:
The product of two numbers is 2400, one number is 20 more than the other number. what are the two numbers?
Answered by Penny Nom.
Related rates 2008-10-16
From Gisela:
As sand leaks out of a hole in a container, it forms a conical pile whose altitude is always the same as its radius. If the height of the pile is increasing at a rate of 6 in/min, find the rate at which the sand is leaking out when the altitude is 10in.
Answered by Penny Nom.
Finding the Raw Score for a Mean of 0 and Standard Deviation of 1 2008-10-02
From Anita:
A variable Y has a distribution of mean of Y =80 and standard deviation of Y=36. Find the values of A and B for transforming y*=A +BY so that mean of y* =0 and standard deviation of y*=1.
Answered by Janice Cotcher.
Is it possible to a function to be both even and odd ? 2008-09-28
From Mohammed:
Is it possible to a function to be both ( Even and Odd )
Answered by Harley Weston.
The standard form Ax+By=C 2008-09-26
From Susan:
I am having difficulty changing the point-slope form of the equation of the line y-y1=m(x-x1) to the standard form Ax+By=C. You must express A,B,C in terms of the constants m,x1,y1. I have been able to insert numbers and switch easily from the general to the point slope equation, but I am stumped on how to convert it this way.
Answered by Penny Nom.
Two consecutive numbers 2008-09-21
From tomas:
what is the two consecutive numbers with a product of 4160?
Answered by Penny Nom.
The percentage of sand in a soil mixture 2008-09-05
From kristi:
2 m 3 of soil containing 35% sand was mixed into 6 m 4 of soil containing 15% sand. What is the sand content of the mixture?
Answered by Penny Nom.
A linear function 2008-08-07
From Warren:
What are the conditions of the numerical coefficients of the standard form Ax+By=C in Linear Function? How will you transform y=square root of 3 x + 1 in standard form Ax+By=C?
Answered by Penny Nom.
Limit as it Approaches Infinity 2008-07-29
From mary:
i was trying to find the limit of this problem the limit as x approches infinity of x minus cosx divided by x lim x-cosx/x x->oo
Answered by Harley Weston.
Problems understanding math 2008-07-27
From Cindy:
why do so many people have problems understanding math. is it because at some point along the way they didn't fully understand a concept and they then lose confidence. Learning math is cummulative so what you don't learn at one point just gets more confusing as you move along. how do we correct this? how can i help students in junior and senior high who do poorly in math.
Answered by Stephen La Rocque and Victoria West.
How much sand do I order? 2008-07-15
From jackson:
We would like to put 2 inches of sand down. The pool is 24 feet. How much sand will we need? The person we spoke to yesterday was talking in tons, but on these sites it is talking cubic yards or feet. Please help. We would like to get the sand ordered so we can get the pool up!
Answered by Harley Weston.
How many handshakes take place? 2008-06-26
From Peter:
Eight people of different heights are at a party. Each person decides to only shake hands with people shorter than him/herself. How many handshakes take place? My math book says it is 0. Is it wrong? If so, what is the answer?
Answered by Harley Weston.
A five card hand of playing cards with all 4 tens 2008-06-25
From shari:
of the 2598960 different five card hands from a deck of 52 playing cards. how many would contain all ten's?
Answered by Janice Cotcher.
I will be x years old in the year x squared 2008-06-22
From rachel:
you probably know someone who will x years old in the year x squared. When was that person born?
Answered by ha.
-2(x - 1)^2 + 8 2008-06-12
From kasondra:
y=-2(x-1)2[thats a square] +8 that need to be put in standard form
the answer is y= -2x2 -4x + 6
i got y= -2x2 -4x -4
i just don't get how my teacher got that answer

Answered by Penny Nom.
Filling a hole with sand 2008-06-05
From greg:
I have a 18 ft. diameter circle and need to put 2 in. of sand in it i need to know how much sand in cubic yards and tons
Answered by Harley Weston.
.5 cu ft of sand to lbs. 2008-05-25
From rogersimmons:
needtocovert .5 cu ft. of sand into lbs.
Answered by Penny Nom.
The standard form of an ellipse 2008-04-30
From Rebecca:
I have to write the following equation into standard form of an ellipse:

9(X-1)^2 + (Y+1)^2 = 1

Answered by Stephen La Rocque and Harley Weston.
A 13 cubic foot cylinder filled with sand 2008-04-12
From Thomas:
I have a 100 pound bag of sand. I need to know how much sand I will need to fill a 13 cubic foot cylinder
Answered by Harley Weston.
The angle between the hands on a clock 2008-04-04
From Kristin:
The question I need help with is : Bobo looked at the clock at 1:25. What was the precise measure of the angle formed by the hour and minute hands of the clock? Assume that each of the clock hands moves at a constant rate continuously around the face of the clock. Thus, in any given fractional part of an hour, each hand will move that same fractional part of an hour's worth of movement.
Answered by Stephen La Rocque.
Expected value and standard deviation 2008-03-19
From Patrick:
Heres a question i cant figure out:
a small airline company has only three flights per day. The number of delayed flights per day is regarded as a random variable, and I'm supposed to calculate the expected value and standard deviation of the number of delays. the probability distribution looks like:
No. of Delays: 0 1 2 3
Prob. of delay: 05. 0.3 .1 .1

Answered by Harley Weston.
Time and a half 2008-03-01
From Travis:
Bill receives time and a half for working overtime. If Bill is paid $55 for each hour of overtime, how much is his regular hourly wage?
Answered by Stephen La Rocque.
Handshakes at a twenty person party 2008-02-25
From Chris:
Twenty people have gathered at a party. Find the number of handshakes when each person shakes hands with everyone else at the party.
Answered by Penny Nom.
The equation of a line 2008-02-17
From Jennifer:
Given the point A(3,2)B(5,8) find the equation of the line AB ( in standard form )
Answered by Penny Nom.
Numbers and Operations 2008-02-02
From Charlotte:
On the TABE (Test for Adult Basic Education) test, one of the categories is number operation. I would like to know what consist of number operation.
Answered by Penny Nom.
The standard form of a line 2008-01-30
From Thomas:
I'm attempting to get this in standard form


Answered by Penny Nom.
The standard form of a line 2008-01-24
From James:
I need to put it in Standard from ax+by=c the problem is (-4,0); parallel to y=-2+1 how can I put this in Standard from
Answered by Stephen La Rocque.
The equation of a line 2008-01-20
From Sara:
The question is:

Write the equation of a line that is parallel to y=3x-2 through the point (-5,9). I think the correct equation for this is y=3x+24. But I have to write it in standard form, and I can't seem to figure out how to do that. Please answer soon! Thanks!

Answered by Stephen La Rocque and Penny Nom.
A 16 sided lot 2008-01-16
From R:
I am having a land of 16 irregular sides i know all the length of the sides how to calculate the area of the land
Answered by Harley Weston.
The standard normal distribution 2007-12-29
Statistics texts state that in a normal distribution, 1 standard deviation covers 68%, 2SD 95% 3SD 99.7%. However, on looking at the tables for normal curve areas, the percentage for a z value of 1 is 84.13. 68 % of values are covered at a z value of 0.47. The discrepancies exist even for other values but are smaller. So why is the rule of thumb so different from the Table for Normal Curve areas?
Answered by Harley Weston.
Mean and standard deviation 2007-12-10
From Jamie:
Let n be any odd whole number.
a) Which has the greater mean: the odd whole numbers from 1 to n, or the even whole numbers from 2 to n-1?
b) Which has the greater standard deviation: the odd whole numbers from 1 to n, or the even whole numbers from 2 to n-1?

Answered by Penny Nom.
Three consecutive numbers 2007-12-08
From Aris:
The product of 3 consecutive numbers is 1716. Find their sum.
Answered by Stephen La Rocque.
Guess and check 2007-12-03
From Marissa:
I was sent home with a guess and check work sheet. i am not sure how i am sopouse to do this.
a sleeping bag and 2 mess kits costs $37.00.A mess kit and two sleeping bags cost $56.00
what is the cost of one sleeping bag.

Answered by Stephen La Rocque.
A t-test 2007-11-20
From Rachel:
I am wanting to use the t-test to find if temperature over a period of 5 days was significantly different to the mean temperature for that time of year. So i want to compare expected temps to actual temps. The problem is that because the expected temperature is the same for the 5 days it gives me a standard deviation of zero. Does this mean the t-test cannot be used because the f-test can't be calculated. If so is there an alternative test?
Answered by Harley Weston.
Standard deviation 2007-11-20
From Shahzada:
when and why we use standard deviation in Data analysis?
Answered by Harley Weston.
Expand (a^4 - b^4) 2007-11-17
From Saif:
how would you expand (a^4 - b^4) ???
Answered by Stephen La Rocque and Victoria West.
Maximize his profit 2007-11-12
From apoorva:
During the summer months Terry makes and sells necklaces on the beach. Last summer he sold the necklaces for $10 each and his sales averaged 20 per day. When he increased the price by $1, he found that he lost two sales per day.

a. Find the demand function, assuming it is linear.
b. If the material for each necklace costs Terry $6, what should the selling price be to maximize his profit?

Answered by Penny Nom.
6 consecutive multiples of 6 2007-11-11
From jeff:
find 6 consecutive multiples of 6 whose sum is the least common multiple of 13 and 18
Answered by Penny Nom.
Stem & Leaf Plots 2007-11-02
From Jen:
Trying to help my Gr.4 son with his math and i am a little lost here are the stem and leaf plots..
Stem Leaves
4          02
3          1226699
2          011255789
1          33357899

Stem Leaves
2          00011111223334455
1          range566788899

Question - How are the ranges for the stem & leaf plots different ?

Answered by Penny Nom.
Dividing a segment into 3 congruent parts 2007-10-30
From Carolyn:
I am doing construction. I have a line segment drawn. I need to divide a segment into 3 congruent part. How do I do that?
Answered by Penny Nom.
Two mirrors 2007-10-24
From Peter:
The reflecting surfaces of two intersecting flat mirrors are at an angle θ (0° < θ < 90°). For a light ray that strikes the horizontal mirror, show that the emerging ray will intersect the incident ray at an angle β = 180° – 2θ.
Answered by Stephen La Rocque.
The distance of the Andromeda Galaxy 2007-10-22
From ROLY:
What is 2.5 million miles x 6 trillion miles (light year)
This is the distance of the ANDROMEDA Galaxy.

Answered by Stephen La Rocque.
the sum of two consecutive integers is 51 2007-10-17
From Keira:
the sum of two consecutive integers is 51
Answered by Penny Nom.
A stem leaf and plot with decimals 2007-10-12
From Brandi:
My child came home with a worksheet regarding stem and leaf plot. I figured out how to work it with whole number but not with decimals. Can you tell me how to do this with stem and leaf graph? They are even asking for a conclusion on the information. This makes no sense to me. Please explain and send an example problem also. Thank you!
Answered by Harley Weston.
Grouped data 2007-10-08
From Nimra:
The following sets of data represent the distributions of
house prices in the north-east and south-west of a country.
Random samples of 100 houses were selected in each region.
(a) Calculate the mean, median and standard deviation for

Answered by Harley Weston.
2 aces and 3 kings 2007-10-05
From Becky:
How many 5-card poker hands consisting of 2 aces and 3 kings are possible with an ordinary 52-card deck?
Answered by Penny Nom.
Maximizing profits II 2007-10-05
From a student:
Suppose there are three firms with the same demand function. The function is Q=1000-40P. Each firm also a a cost function.
Firm 1: 4000+5Q, Firm 2: 3000+5Q, Firm 3: 3000+7Q.
What price should each firm charge if it wants to maximize profits.

Answered by Harley Weston.
Sum and difference of two mystery numbers 2007-10-04
From Donna:
The sum of two numbers is 39. The difference is 11. What are the numbers?
Answered by Stephen La Rocque.
Gas and oil at a 50:1 ratio 2007-10-03
From Cindy:
How much gas and oil do you put in a 1.7 litre jug at a 50:1 ratio?
Answered by Stephen La Rocque.
How many ten thousands makes one million? 2007-10-02
From Payton:
how many ten thousands makes one million?
Answered by Penny Nom.
How many two digit numbers contain at least one 7? 2007-09-06
From Janet:
How many two digit numbers contain at least one number seven?
Answered by Penny Nom.
Standard deviation 2007-09-05
From Ethan:
Okay I have a question about standard deviation. Can you tell me a five number set of data that will have a standard deviation f zero and how you know that?
Answered by Stephen la Rocque.
Standard deviation 2007-09-01
From Pat:
I have looked over your math question and mines is not there. for a binomiial distribution with parmeter n and p, the mean is np and the standard deviation is np(1-p). I understand how to get the np but not understanding how to get the (1-p). For example np=(40)(0.48)(1-0.48)=3.160. How can I get the (1-0.48) answer please
Answered by Harley Weston.
32,648 square footage = how much land? 2007-08-22
From Elizabeth:
1. What amount of Land = an acre?
2. 32,648 square footage = how much land?

Answered by Penny Nom.
A statistics example 2007-08-02
From Claudia:
A particular employee arrives to work some time between 8:00 am - 8:30 am. Based on past experience the Company has determined that the employee is equally likely to arrive at any time between 8:00 am - 8:30 am.

On average, what time does the employee arrive?

What is the standard deviation of the time at which the employee arrives?

Find the probability that the employee arrives exactly at 8:12 am?

Find the probability that the employee arrives between 8:20 am - 8:25 am?

Answered by Har.
A football stand 2007-07-19
From jean:
a football stand 150 yd. long has 20 tiers of seats; each has a rise of 2 ft. and tread of 3 ft. it constructed of reinforced concrete with a cross section of 36*54. find the amount of material used in its construction.
Answered by Harley Weston.
Calculating the area (acreage) of a four sided lot 2007-07-18
From A property owner:
I have a real estate property and the lot size is something I need to find out. I know the lengths of the four sides, but it isn't a rectangle, it is an odd shape. How do I find the acreage?
Answered by Stephen La Rocque.
Algebraic EquationsAx+By=C 2007-07-02
From Juan:
The general "Standard" form of an equation is Ax+By=C. Re-Write this equation in slope-intercept (y=mx+b) form.
Answered by Harley Weston.
How many tons of sand? 2007-06-19
From Richard:
I need to know how many tons of sand it would take to fill a container 20 feet long, 20 feet wide, and 6 inches deep. I am not sure of the makeup of the sand as far as dry, loose, wet, etc. If you could give me calculations of all the variants it would be appreciated.
Answered by Stephen La Rocque and Penny Nom.
Standard Deviation 2007-06-13
From Adrian:
If you are told that the mean salary of a certain group of workers is $30,000 with a standard deviation of $4000, what proportion of workers earn over $38,000? What proportion of workers earn less than $18,000? Assume the distribution of wages is normal.
Answered by Stephen La Rocque.
What are the odds that the selections were random? 2007-05-26
From alan:
An employer must select three people for layoff from three groups. Group 1 has 4 members and the oldest member is selected. Group 2 has 7 members and the oldest member is selected. Group 3 has 2 members and the younger is selected. Assuming equal qualifications, what are the odds that the selections were random vs. biased as to age? What is the formula to determine this?
Answered by Penny Nom.
Normal distribution 2007-05-24
From Paula:
Consider a data set that is normally distributed. The mean of the data set is equal to 10,000.
a.) Suppose that, for this data set, 10,625 has a "z-value" = 2.5. Solve for the standard deviation of the data set.
b.) Solve for the "z-value" of 9,900.

Answered by Penny Nom.
Using a stem and leaf plot 2007-05-22
From Maegan:
The students in Mr.Smiths PE class collected data on the number of sit ups the students were able to do in three minutes. Use the data to create a stem and leaf plot. What is the median for the class data? range? mode?
Answered by Penny Nom.
Converting mass of sand to volume (a sand ceremony) 2007-05-21
From Linda:
I'm getting married. We are having a sand ceremony. The empty bottle we are using holds 800ml. I have bags of colored sand. Each bag is 30g. There is 7 people participating in this ceremony. What I need to find out is how many grams of sand i need for 7 people to participate to fill this jar.
Answered by Penny Nom.
Constant rate of sand falling in a cone 2007-05-20
From Nhi:
Sand is falling into a conical pile . After 5 min. the pile has radius 24 and height 26 . After 7 min. tell how far the point c. is from the top of the cone (A).
Answered by Stephen La Rocque.
(3x-2(x-3)+2)(3x-2(x-3)+2) 2007-05-17
From Jeff:
Answered by Penny Nom.
Cubic feet of sand 2007-05-09
From Paul:
I have an above ground pool that is 585 sq feet. I want to cover the bottom in 3 inches of sand. The sand supplier says I need about 6 cubic yards, based on your prior answers on this subject. I come up with 1.8 yards. What is the correct amount?
Answered by Stephen La Rocque.
Who was the mathematician that united algebra and geometry? 2007-05-08
From Victor:
who was the mathematician that united algebra and geometry
Answered by Penny Nom.
A thousand, is it M or K? 2007-05-01
From Larry:
I have heard that Million is annotated as MM. But Ihave heard two answers for Thousands (K, M). Which is correct?
Answered by Penny Nom.
Incremental standard deviation 2007-04-28
From Murtaza:
Hi In relation my question asked earlier, i would first like to thank you for the prompt reply. But it has not answered my query yet. Let me frame the problem again. I have a mean value for N data items. (note that i know N but i donot know the distinct N data item values) Now the (N+1)th data item comes in and i calculate the new mean. (incremental method for that is simple). How do i calculate the new standard deviation. The formula you gave me requires me to read the data items once and at the end of the pass i will have have the standard deviation. But i need the STDDEV values at intermediate stages as well. Is it possible ? Murtaza
Answered by Penny Nom.
How many tons of sand is needed 2007-04-25
From Jennifer:
How many tons of sand is needed to cover 350 cubic square feet?
Answered by Penny Nom.
A box-and-whisker plot with no whiskers 2007-04-18
From Paula:
Is it possible for a box-and-whisker plot to have no whiskers? 3 whiskers?
Answered by Penny Nom.
Intersection of a line and a circle 2007-04-12
From gaby:
The sum of two numbers is 9. The sum of the squares of the two numbers is 41. Find the numbers.
Answered by Steve La Rocque and Melanie Tyrer.
A one pass calculation of standard deviation 2007-03-19
From Murtaza:
Hi I searched the listings but couldn't find what i am looking for. I have a dataset and i am allowed only 1 pass through it. At the end of this pass i must have the mean and standard deviation. Calculating the mean is easy as also demonstrated in your listings. I think the same can be done for standard deviation as well. But the doubt that i have is this :- Will the calculated standard deviation be sequence dependent ? i.e. if i change the order in which the data items enter the system, will the std deviation also change ?? Thanks in advance Murtaza
Answered by Penny Nom.
Nickels, dimes and quarters 2007-03-18
From Alexandra:
Ellen has two more nickels than dimes and three more quarters than nickels. She has $3.35 in all. How many coins of each type does she have?
Answered by Penny Nom.
A stem and leaf plot 2007-03-14
From Hazel:
Hi, I wanna ask about my son's homework re: reading stem and leaf plots. It's really hard for me to understand about this..please show me how. Ex. Number of dogs competing in dog shows

Stem Leaf
1 62024
2 5295
3 166
4 05

1. What was the least number of dogs at a dog show?
2.What was the greatest number of dogs at a dog show?
3. How many dogs shows are reported in the stem and leaf plot? thanks...Hazel

Answered by Penny Nom.
Concrete sand 2007-03-08
From david:
Can you tell me how much 4 cubic yards of concrete sand ways in tons? THANK YOU.
Answered by Stephen La Rocque.
Chickens and cows 2007-02-08
From Norman:
My grandson is testing me on a question he recently solved.

The question is "A farmer has cows and chickens - there are 252 heads and 81 legs - how many of each animal does he have?"

I immediately thought of the quadratic equations I learned 50 years ago at school, but cannot remember how to do it. It is further complicated by the fact that 1 animal must have 3 legs as the total number of legs is 81 (or perhaps he his trying to catch me out) Any helpful advice would be welcome.

Many thanks

Answered by Stephen La Rocque and Penny Nom.
Guess and check 2007-01-17
From Gwen:
scott has 13 music boxes that play either patriotic songs or holiday tunes.he has 5 more music boxes that play holiday tunes. how many of each kind does he have
Answered by Penny Nom.
Standard deviation 2007-01-15
From Kayleigh:
After i have added up all the squared deviations what do i do???, what is meant by "divide by one less than the sample size"
Answered by Stephen La Rocque.
The absolute value of imaginary and complex numbers 2006-12-11
From Keith:
i don't get how to find the absolute value of imaginary and complex numbers here is an examples from the text book the answers are given but they don't show the work so i can follow along just show me the work please and explain how it is done


Answered by Stephen La Rocque and Penny Nom.
The name of an equation 2006-11-13
From Lee:
I am struggling to find the name of the following equation. I remember watching a TV programme introduced by Arthur C Clarke. The programme focused on an equation that gave a wonderful pattern that went on into infinity. Two maths professors discussed this equation.It was described as 'Gods equation' as it was compared to the shape of trees and other shapes in nature. It was named after the inventor/discoverer. If you have any ideas i would be most grateful.
Answered by Penny Nom.
Ratios, proportions and medicine 2006-10-25
From Steven:
I don't understand why we need to learn about ratios and proportions because i want to become a doctor and i don't know if i'll ever use this type of math.
Answered by Penny Nom, Claude Tardif and Walter Whiteley.
How do you find the length and width of a rectangle if you know ... 2006-10-15
From Anne:
How do you find the length and width of a rectangle if you know the perimeter of the rectangle is 48 m and the area is 144 m squared?
Answered by Stephen La Rocque and Penny Nom.
Standard deviation 2006-10-04
From Jennifer:
I was wondering how to figure out a standard deviation if you only have the mean of the data and no other information?
Answered by Stephen La Rocque.
The area of my hand 2006-10-02
From Waikiki:
is there a possible way for me to calculate the area of my hand (palm and fingers involved)? obviously it is curved and i can't find a way on how to solve it...
Answered by Chris Fisher and Diane Hanson.
Cubic yards of sand 2006-09-20
From Michael:
How many compacted cubic yards of sand are there in 40 acres of land at a depth of 20 feet?
Answered by Stephen La Rocque.
Convert a standard form to a slope intercept form 2006-09-14
From Maiko:
I need to know step by step procedures to convert a standard form to a slope intercept form?
Answered by Penny Nom.
10,000 Million sandwiches 2006-09-12
From A business person:
One of our customers said that the UK sells "10,000 Million" sandwiches annually in their take away restaurants... How many is this exactly?
Answered by Stephen La Rocque.
How many thousands are in ten million. 2006-08-24
From Echoe:
How many thousands are in ten million.
Answered by Stephen La Rocque.
Cubic yards of sand 2006-05-26
From Steve:
I need to cover an area with sand that is 30 feet wide and 60 feet long and I need the depth of the sand to be 1/4 inch thick. How many cubic yards of sand will I need?
Answered by Penny Nom.
Landscaping 2006-05-11
From Luke:


Answered by Stephen La Rocque.
How many thousands make 1million? 2006-05-10
From Raj:
How many thousands make 1million?
Answered by Penny Nom.
Absolute Value vs. Standard Deviation ? 2006-04-24
From Sonia:
Why we don't just take the average of the absolute value of difference scores (use the mean deviation) to describe variability instead of calculating the standard deviation?
Answered by Claude Tardif.
Cubic yards of landscape stone 2006-04-19
From Janet:
I need to spread landscape stone around my pool. A landscaper said I need 16 yards. What is the area of a cubic yard if I want the stone 3" deep?
Answered by Stephen La Rocque.
How many students and how many cookies are there? 2006-03-10
From Stephanie:
A group of students is trying to evenly divide the cookies remaining from a bake sale. If each student takes three cookies, there are five cookies left. If each student takes four cookies, they are two cookies short. How many students and how many cookies are there?
Answered by Penny Nom.
Stem-and-leaf plots, box-and-whisker plots and medians 2006-02-21
From A student:
explain which plot would be easiest to use to find the median....box-and-whiskers plot or stem-and-leaf plot
Answered by Penny Nom.
Outliers in a box and whisker plot 2006-02-19
From A student:
i need help on determining if their is an outlier...i know how to find the median and the lower quartile and the upper quartile..but i don't understand about the outliers....please tell me if their is an outlier in this problem....the numbers are...63,88,89,89,95,98,99,99,100,100
Answered by Penny Nom.
Whose photo is he looking at? 2006-02-19
From Adeyeri:
Looking at a picture a man says, that the father of the person (in photo) is the son of my father. whose photo is he looking at?
Answered by Penny Nom.
How many beanbag animals does each friend have? 2006-02-09
From A student:
Melissa has 1 more than twice the number of beanbag animals Rachael has. Latanya has a third as many bean bag animals as Melissa has. Together, the three friends have 38 beanbag animals. How many beanbag animals does each friend have?
Answered by Steve La Rocque and Penny Nom.
I need to order sand for playgrounds 2006-01-18
From Jody:
I need to order sand for playgrounds. I have their square footage and the various depths of sand needed for each, but sand comes in tons.

What is the formula for converting square footage and depth to tons (for example: 6 inches of sand needed for a 200sq ft area = how many tons?)

Answered by Penny Nom.
Mrs. Faria lives on an island 2005-12-15
From Julie:
Mrs. Faria lives on an island 1 km from the mainland. She paddles her canoe at 3 km/h and jogs at 5 km/h. the nearest drug store is 3 km along the shore from the point on the shore closest to the island. Where should she land to reach the drug store in minimum time?
Answered by Penny Nom.
A standard normal probability 2005-11-19
From Pat:
Find the probability of Z when it lies between -1.10 and -0.36
Answered by Penny Nom.
Two word problems 2005-11-14
From Jennifer:

1. Every other person on a school's parent advisory committee is surveyed to determine how many people support passage of a school bond to build a new elementary school. Is this a good sample? Why or why not?

2.What is the difference in elevation between the highest point in California,Mount Whitney,which towers 4421 meters above sea level, the lowest point in California,Death Valley, which lies 86 meters below sea level?

Answered by Harley Weston.
Mario is 16 years older than his youngest sister, Mercedes. 2005-11-08
From Jennifer:
Mario is 16 years older than his youngest sister, Mercedes. Together, their ages total 36 years . How old is each person?
Answered by Paenny Nom.
Guess and Check 2005-11-01
From Robin:

Greta has a vegetable garden. She sells her extra produce at the local Farmer's Market. One Saturday she sold $200 worth of vegetables --peppers, squash, tomatoes and corn.

Greta received the same amount of money for the peppers as she did for the squash.

The tomatoes brought in twice as much as the peppers and squash together.

The money she made from corn was $8 more than she made from the other three kinds of vegetables combined.

How much did Greta receive for each kind of vegetable?

Answered by Penny Nom.
A sum of 75 and a difference of 13 2005-10-30
From Vicki:
Find two numbers that have a difference of 13 AND A SUM OF 75? We need to learn about the formula or procedure.
Answered by Penny Nom.
A random sample 2005-10-16
From Stu:
If I have a set of data points (14 to be exact)of unknown pedigree from a large population, what tests can I apply to see if they constitute a random sample from the large population?
Answered by Andrei Volodin and Penny Nom.
Means of sample means 2005-10-12
From Fareeha:
A population consists of six numbers 1,2,3,4,5,6
a) How many different samples of two numbers can be selected with replacement? and list them.
b) Calculate the mean and standard deviation of the population
b2) Calculate the mean and standard deviation of the mean of the samples.
c) Find the standard error of your estimated mean in question b2 and compare with the estimated standard deviation in b2.

Answered by Penny Nom.
There are 28 boys and girls in a class.... 2005-10-09
From Clement:
There are 28 boys and girls in a class. Each boy collects 10 stamps and each girl collects 9 stamps. The boys have 90 stamps more than the girls. How many boy and how many girls are there?
Answered by Penny Nom.
Constructing figures 2005-09-20
From Kim:
I would like to know how to draw different shapes:
Regular Octagon with sides of length, 1 unit
Equilateral Triangles, with sides of length 1 unit
Regular Hexagons, with sides of length 1 unit
Isoseles Triangles, with hypotenuse of length 1 unit

Answered by Penny Nom.
A normal distribution problem 2005-08-08
From Brad:
The life of a toy is normally distributed. Suppose 92.51% of the items lives exceeding 2,160 hours and 3.92% have lives exceeding 17,040 hours. Find the mean and the standard deviation.
Answered by Penny Nom.
Cubic yards of sand 2005-08-04
From Beth:
I am trying to figure out how much sand I will need for ground cover under my children's playset. The area to cover is 30' x 30' and I want 4 inches of sand.
Answered by Penny Nom.
Cubic yards of sand 2005-04-27
From Renee:
I need to find out how much sand I would need to order for the base of a horse round pen. The pen is 40 ft across and I would like a depth of 4 inches. I have to order the sand in cubic yards.
Answered by Penny Nom.
How much sand is in a pile? 2005-04-16
From Larry:
I was wondering if there is a formula for determining how much sand would be in a pile. I am a student in medical school, and this is a bonus question for a test. I hope you can help me.
Answered by Harley Weston.
Standard deviation 2005-01-02
From Urial:
Find the standard deviation of the given data set
To get the best deal for CD dealer, Jessica called eight appliance stores and asked the cast of a specific model. The prices she quoted are listed below.

$300, $203, $272, $332, $440, $119, $129,$254

Answered by Penny Nom.
A standard deviation test 2004-11-09
From Karen:
How do you compare to see if a sample standard deviation is different than the population standard deviation? I know how to compare means, but not standard deviations.
Answered by Penny Nom.
A five digit number 2004-10-06
From A parent:
What is the 5 digit number in which the first 2 digits are the square of the 3rd digit and the last 2 digits are the square of the digit that is one less than the third digit? The sum of all the digits is 22.
Answered by Penny Nom.
Incremental variance 2004-09-23
From Carlos:
I must keep statistical data (mean and variance) in 3 granularity levels depending on the age of the data (daily for older than 1 year, hourly for older than 1 month and quarter-hour for older than 1 day). How can I calculate the resulting variance from a set of variances previously calculated supposing I have the count and mean for each member of the set?
Answered by Andrei Volodin and Penny Nom.
The price of a book 2004-09-18
From Dorly:
If the number of toonies required to buy a book is nine more than the number of five-dollar bills required to buy the same book, determine the cost of the book.
Answered by Penny.
The area of a lot 2004-08-22
From Cassie:
I'm in the process of purchasing some land and I'm trying to figure out the square footage of the property. Unfortunately, it's be a while since I had to remember this type of formula. The property is 140 ft on left side, across the back it is 220.61 ft, the right side is 167.52 ft, the frontage is 105 ft.
Answered by Penny Nom.
Three dice 2004-05-10
From A student:
If one has 3, 6 sided dice what is the probability of the numbers that are rolled to total 4 through 10 inclusively?

Subsequent to this, what is the probability to do this consecutively...say 3 times?

Answered by Peny Nom.
Billions and more! and even more! 2004-03-01
From Steph:
What comes after undecillion?
Answered by Penny Nom.
Two consecutive negative integers 2004-01-17
From Amanda:
Find two consecutive negative intergers whose product is 182.
Answered by Penny Nom.
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.

Answered by Andrei Volodin.
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?
Answered by Penny Nom.
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.
Answered by Penny Nom.
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
Answered by Penny Nom.
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???

Answered by Penny Nom.
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?
Answered by Penny Nom.
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.

Answered by Penny Nom.
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???

Answered by Penny Nom.
Notation 2003-09-15
From Kim:

i have a couple of questions

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


Answered by Penny Nom.
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)
Answered by Penny Nom.
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.

Answered by Leeanne Boehm.
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?
Answered by Penny Nom.
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?
Answered by Penny Nom.
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 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

Answered by Penny Nom.
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
Answered by Penny Nom.
Sasha's candies 2003-02-18
From Pat:

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?

Answered by Paul Betts.
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?

Answered by Penny Nom.
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.

Answered by Penny Nom.
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.
Answered by Harley Weston.
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.
How many billions equal one trillion? 2002-12-07
From Ryan and Aylah:
How many billions equal one trillion?
We believe that the answer is one thousand times one billion equals one trillion. Please help us with the answer to this question.

Answered by Penny Nom.
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.

Answered by Penny Nom.
Radicals with fractional radicands 2002-11-11
From A student:
how do I simplify radicals with fractional radicands?

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

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

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

Answered by Penny Nom.
Variance 2002-10-29
From Ade:
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.
Answered by Andrei Volodin.
Nixon, Jefferson, and Madison 2002-10-08
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?
Answered by Penny Nom.
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?
Answered by Penny Nom.
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.
Answered by Penny Nom.
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?

Answered by Leeanne Boehm.
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.
Answered by Penny Nom.
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?

Answered by Andrei Volodin.
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,

I dont know if these answers are right please help me out.

Answered by Andrei Volodin.
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

Answered by Penny Nom.
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).

Answered by Penny Nom.
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?
Answered by 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?
Answered by Andrei Volodin.
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?
Answered by Penny Nom.
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?
Answered by Penny Nom.
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?
Answered by Penny Nom.
For 7 the multiplicand is 143 2001-12-12
From Cory:
For 7 the multiplicand is 143

I am asked to solve this, if you could help me it would be greatly appreciated!

Answered by Penny Nom.
Box and Whisker plots 2001-11-19
From Rod:
In our Prealgebra course, we have been studying Box and Whisker plots. Recently, we learned how to decide whether a data point is an outlier or not. The book (Math Thematics, McDougall Littell) gave a process by which we find the interquartile range, then multiply by 1.5. We add this number to the upper quartile, and any points above this are considered to be outliers. We also subtract the number from the lower quartile for the same effect.

My question: where does this 1.5 originate? Is this the standard for locating outliers, or can we choose any number (that seems reasonable, like 2 or 1.8 for example) to multiply with the Interquartile range? If it is a standard, were outliers simply defined via this process, or did statisticians use empirical evidence to suggest that 1.5 is somehow optimal for deciding whether data points are valid or not?

Answered by Penny Nom.
Renee, Paulo and Peter 2001-11-18
From Sue:
Renee is 5 years older than Paulo. she is also 7 years older than Peter. The sum of their ages is 21. How old is each person.
Answered by Penny Nom.
Tenths, hundredths, and thousandths 2001-10-17
From Cheri:
I would like the French terms for the decimal place values of tenths, hundredths, and thousandths. (I would be interested in the Spanish terms also if you had them.)
Answered by Maria Torres and Claude Tardif.
Joan and Jan work together 2001-09-26
From Karyna:
Joan and Jan work together and they set up a bandstand in just 24 minutes, but if Joan does it by herself she takes 1 hour. How long would it take Jan to set up the bandstand by himself?
Answered by Claude Tardif.
Ciefficient of variation 2001-09-23
From Carmen:
I have a question from my OAC finite class. I've come across a problem with the coefficient of variation. I have taught my students that there are no units for coefficient of variation and it can be expressed as a percent. So, for example, a set of data with mean of 5 and standard deviation of 100 would have a CV of 5%. But what happens in this situation: the mean is 4meters and the standard deviation is 0.7mm. Is the CV 1.75% or 0.00175% or 0.0175%? I've had some students change leave the units as is, change them both to mm or change them both to meters...so which is it and why?
Answered by Penny Nom.
Standard deviation 2001-09-22
From Doug:
I was wondering if anybody knows who the founder of standard deviation was?
Answered by Penny Nom.
Standard angles 2001-08-05
From Nagaraj:
Why 0o , 30o , 45o , 60o ,and 90o are taken as standard angles in Trigonometry? Why can't we take some other angles as standard angles?
Answered by Chris Fisher.
Linear regression 2001-08-01
From A student and a mother:
My mom is taking a correspondence course in Simple Linear Regression and Correlation Analysis and we've been arguing about the relationship between the correlation -rxy and standard estimate of error-Sy.x. I took statistics last year in high school and I remember something about the Sy.x being proportionate to the r. Are they inversely related, directly related, not related, or can only range from 0 to 1.00? Her book doesn't say very much and I believe they are inversely related. She says they're directly related.
Answered by Chris Fisher and Penny Nom.
Comparing means and standard deviations 2001-07-11
From Shelly:
Is there a way to compare means and standard deviations that come from different size samples? Is there an equation that can normalize sample size?
Answered by Andrei Volodin.
Chickens and sheep 2001-05-31
From Monica:
Farmer Bob of the Martian Colony counted his sheep and chickens in an unusual way. When he finished, he reported that he had counted 86 feet and 26 heads. Use a guess and check table to find how many sheep and chickens are owned by the famer.
Answered by Paul Betts and Penny Nom.
A pile of sand 2001-05-14
From Gul:
  1. Sand for use on icy roads is stored in a conical pile 14.2 m high and with a base diameter of 34.4 m
    • calculate the volume of the pile

    • if one sander can take 6.9 m of sand, how many sanders can be filled from the pile?

Answered by Penny Nom.
Sigma 2001-03-31
From A student:
What does the Sigma symbol mean in mathematics?
Answered by Penny Nom.
Stem-and-leaf plot 2001-03-29
From Kelly:
I'm tutoring my 5th grade nephew, and he needs to correct test questions regarding a stem - and - leaf plot. He left his book at school and I'm not familiar with the term. Can you explain it to me so that I can help him?
Answered by Penny Nom.
4160 2001-03-07
From Jessica:
The product of two consecutive page numbers in this book is 4160. What are the page numbers?
Answered by Penny Nom.
A four dimensional object 2001-02-14
From A student:
Can you give me some examples of a four dimensional object you can find around your house?
Answered by Harley Weston.
Two questions 2001-01-04
From Justine:
first: A diagonal of a rectangle is the square root of 13 meters and the area of the rectangle is 6 meters squared. What are the dimensions of the rectangle?

last: Find the ordered triple of nonzero digits (A,B,C) for which (AA)squared=BBCC where AA and BBCC are respectively, two-digit and four-digit base-ten numerals.

Answered by Penny Nom.
Cats and dogs 2000-12-24
From A student:
Brian has fourteen pets. All of his pets are cats and dogs. Brian has four more cats than dogs. How many dogs does he have?
Answered by Penny Nom.
Dividing fractions 2000-10-18
From Paula:
Why do you have to change the division sign to a multiplication sign and invert the fraction that follows the division sign in order to get the answer to a division problem when you're working with fractions?
Answered by Penny Nom.
A conic in standard form 2000-05-18
From Tara McConkey:
Im havign trouble converting the following conic to standard form, i know that the conic is a hyperbola but that is all 16x2-9y2-160x-18y+247=0
Answered by Harley Weston.
Uniting algebra and geometry 2000-04-16
From Beth:
Who is the mathmatician that united algebra and geometry???
Answered by Claude Tardif.
Sample variance 2000-04-16
From Jonathan Freeman:
I was just reading your article entitled "A Note on Standard Deviation" I'm now teaching a unit on s.d. and my students were wondering why one uses a denominator of n for a population and n-1 for a sample. I saw in your article that this is because "[the quantity] tends to underestimate sigma... and other technical reasons." To which my students again asked... "Why?" Could you please elaborate a bit on the "other technical reasons" perhaps in terms a high school senior (or their teacher...) could understand?
Answered by Harley Weston.
Box and whisker plots 2000-03-09
From Brett Blake:
Do you have any information on Box and whisker graphs?
Answered by Harley Weston.
Factoring, primes, GCF and LCM 2000-02-27
From Ruth Kroek:
My son is in grade seven, he has to do a Factoring Booklet the areas covered are:
  • Prime #'s
  • Composite #'s
  • Rainbow Factoring
  • Finding Multiples (consecutive multiples)
  • Finding GCF of 2-3 numbers uning Rainbow factoring
  • Finding LCM of 2 numbers using consecutive multiples
  • prime factor trees
  • prime factor ladders
  • finding GCF of 2 numbers using Prime number Method
Although his text 'Math Power' gives some information, we are at a loss ..

Answered by Penny Nom.
Frogs and lily pads 2000-01-23
From Nick:
There are 5 lily pads and 4 frogs, 2 Red and 2 Green, how many moves does it take for them to swap sides?
Answer: 8

I have a formula which will tell you how many moves it will take with different total numbers of frogs, it is [(F*F)/4]+F Where F is the number of red frogs add the number of Green frogs. This formula only works with numbers of frogs that are the same on each side. What I would like to know is why this formula works and why you have to divide it by 4?

Answered by Penny Nom.
Two candles 1999-11-24
From Skip Simpson:
You have two candles the same length. They are lit at the same time. One burns down in 4 hours; the other in 5 hours. How long does it take before one candle is three times the length of the other candle?
Answered by Walter Whiteley.
Estimating the population mean 1999-11-13
From John Barekman:
Statitistics: Estimating the population mean when the standard deviation is known:

I am not sure which n to use in the formula for the confidence interval equation:

x +/- z*(standard deviation/sqrt(n))

If we have data of ten people, and if we have the data of ten sets of ten people each, what is the difference in the n that we use? What is the difference between the standard deviation and the standard error? Are we using the number of sampling means or just the number of samples?
Answered by Harley Weston.

A donkey and his carrots - part 2 1999-10-02
From Sarah Klink and Brenda Gamble:
Does anyone know the solution of the donkey who had to carry 3000 carrots to the market which was 1000 miles away? The donkey can only carry 1000 carrots at a time and he eats one carrot every mile he walks but this is only when he is carrying carrots. How many carrots can get to the market with the donkey carrying them?
Answered by Claude Tardif.
Stem and Leaf Plot 1999-09-14
From Jeanette Sovick:
My 5th grade son brought home a math paper, the title of which reads, Reading Stem-and-Leaf Plots...can you explain this so I can explain it to him...There is no book, his teacher just sent this practice sheet home for him to complete and I have no clue!
Answered by Penny Nom.
Y2K? 1999-09-03
From Mike Putzakulish:
In Y2K, the "K" stands for thousand, but where did the "K" come from? I know it's not a Roman Numeral, but what is it??
Answered by Chris Fisher and Harley Weston.
Invert and multiply 1999-08-28
From Debbie Walter:
I have another question please, WHY do we invert and multiply when dividing fractions? I know that's what we do but WHY? What is the reasoning behind it?
Answered by Penny Nom.
Standard Deviation 1999-07-11
From Anthony Fama:
I have seen several answers to this question: If one standard deviation represents 68% of the population, what does two, three, four and five sigma [std deviation] represent? As stated, I have seen several different answers and thus, the impetus for my question.
Answered by Harley Weston.
The three cousins 1999-06-01
From Irena:
I have three cousins on my dad's side. The product of their ages is 84. Next year the youngest will be 1/4 the age of the middle cousin. In 2 years from now, the oldest will be twice the current age of the middle. What is the age of my oldest cousin?
Answered by Harley Weston.
Parallel and perpendicular lines 1999-04-23
From Crystal Pilling:
My name is Crystal Pilling and I am in 9th grade algebra. We are currently studying parallel and perpendicular lines. I am having trouble with this problem: 3/4x - 5y= 16, (5,-6) I have to find a line that is perpindicular to this line on a graph.

Answered by Penny Nom.
Standard Form 1999-03-30
From Pam:
How do you put this equation into standard form?


Would you please put this equation in this form Ax+Dy+C=0
Answered by Penny Nom.

A handshake problem 1999-01-05
From Nick Lam:
There are 40 people at a party. 1 host couple, a mom and her daughter. There are 19 other guest couples, composed of moms and their daughters. The Host couple shakes hands with everyone except each other. Each guest mom shakes hands with everyone but their own daughter. Each guest daughter shakes hands with everyone except their own mom. A hand shake between two people is considered to be one handshake. HOW MANY HANDSHAKES ARE THERE?
Answered by Penny Nom.
Random 1998-09-15
From Hugh Ballantyne:
I am an occasional teacher.
Here is my question:
Does the word "random" have a technical meaning in mathematics?

Answered by Harley Weston.
(1+z+z^2)^2 1998-09-10
From A.R.:
These questions deal with factoring.

(1+z+z^2)^2 and (p^2-pq+q^2)^2

I partially understand the second line which would be 1+z^2+z^4+2z+2z^2+2z^3 but I don't understand where the 2 comes from in the second half of that line.

p.s.(^2 means squared or cubed etc.)

Please help me out A.S.A.P.!
I have a quiz on this tomorrow!
Answered by Harley Weston.

Frieze Patterns 1998-08-19
From Brian Bairstow:
I am doing a research project on frieze patterns (also called band patterns or border patterns). I know that there are exactly seven different types of frieze patterns, but I have been unable to find a proof for this. If you could tell me this proof, or tell me some internet sites on which I can find material on this, I would be very grateful.
Answered by Chris Fisher.
Mean and Standard Deviation 1998-04-22
From Kit:
i have a problem of maths.
i think the level of the question is secondary. question: Find the mean and the standard deviation of the numbers:1, 3, 4, 5, 7. i hope u solve this question.
thank you so much!

Answered by Harley Weston.
Hour Hand Movement 1998-04-19
From Chris and Angela Bradley:
My wife and I are haveing an argument over the answer to this question, what is the total number of degrees through which the hour hand of the clock moves in 3 hours and 18 minutes?
Thanks in advance.

Answered by Chris Fisher.
Guess and Check 1997-11-25
From Don Ramey:
Hope you can help !!!! my daughter is in the 4th grade.. she has brought home a homework paper and the subject is problem solving. she does not understand what is expected of her. I have tried to help, but I do not understand either.

She is to use the Guess and check Strategy.

Ben knows 100 of his neighbors by name. Ten are fish. The rest are frogs and turtles. He knows the names of twice as many turtles as frogs. How many turtles does he know by name.?

Please help by explaining the guess and check strategy for a problem like this.
Answered by Diane Hanson.

The Central Limit Theorem 1997-04-21
From Donna Hall:
A skeptic gives the following argument to show that there must be a flaw in the central limit theorem:
We know that the sum of independent Poisson random variables follows a Poisson distribution with a parameter that is the sum of the parameters of the summands. In particular, if n independent Poisson random variables, each with parameter 1/n, are summed, the sum has a Poisson distribution with parameter 1. The central limit theoren says the sum tends to a normal distribution, but Poisson distribution with parameter 1 is not normal.

What do you think of this argument?
Answered by Neal Madras.

Smith, Rodriguez and Jones 1996-11-07
From Rafayel Ambartsumyan:
On a train, Smith, Rodriguez, Jones are the fireman, brakeman, and engineer, but not in that order. Also aboard the train are three businessman who have the same names, a Mr. Smith, a Mr. Rodriguez, and a Mr. Jones. ..... Who is the engineer?
Answered by Penny Nom.
Thousands, millions, billions and trillions 1996-08-22
From Blaine:
What are the names of the periods in groups of numbers like 123,456,789. I need to know the names of them for school. I already know the first ones: units thousands millions billions trillions.
Answered by Penny Nom and Diane Hanson.
Le plus grand commun diviseur 2009-11-11
From Katie:
Question: Pendant mon cours de MAT 1300, mon enseignant m'a posé la question suivante:

(a, b) = 12
(a², b) = 24
(b, 72) = ?

Pouvez-vous m'aider s'il-vous-plaît?

Answered by Claude Tardif.
quel sont les plus grands diviseurs communs? 2005-09-07
From Sylvain:
quel sont les plus grands diviseurs communs?
Answered by Claude Tardif.



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