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 Topic: mean
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The average height of a wall 2019-08-15
From Jeff:
Trying to figure the average height of a sloped foundation wall.
The lowest point is 24 inches or 2 feet.
The highest point is 116 inches or 9’ 8 inches.
Can this be figured without the degree of slope or can we assume it is Equaled sloped from point a to point b. Thanks

Why Mean? 2019-05-08
From Jill:
A group of teachers were trying to figure out why the”mean” is called mean - do you know??
How many students passed the test? 2018-07-20
From florian:
In Mr. Edgecomb's math class, 30 students took an exam on statistics. If the average passing grade was 84, the average failing grade was 60, and the overall average was 80, how many students passed the test?
The mean and median 2018-03-24
From Myrte:
Is the median always smaller then the mean?
60% as much as \$30. 2014-07-18
From Kenneth:
Question from Kenneth:

Hello:

Do you know why some "as...as" phrases indicate multiplication?

For example, ? is 60% as much as \$30. This is equivalent to 60% X \$30 = \$18. How does this make sense?

I saw this example in an old textbook on business mathematics, but the author did not explain why it is equivalent to multiplication.

An error in finding the mean 2013-02-25
From Abhishek:
Mean of 50 observations was found to be 80.4 but later all it was discovered 96 was mistake at 69 Find the correct mean?
What was the class average? 2012-04-20
From olwale:
a class which consist of 15 boys and 10 girls sit for a test. the average score of the boys is 20 and the girls' is 25. find the average score of the class.
The same mean but different ranges 2012-01-14
From swathi:
Frank and Frances work out at their local gym. the mean of their workout times is the same: 48 min. however, the range of Frank's workout times is 7 min, while the range of Frances'sworkout times is 16 min. explain how this is possible.
Mean and Average 2012-01-03
From john:
what is the difference between average and mean
The average age of 300 cars 2011-11-22
From Jason:
I have 300 used cars built from 1970 to 1980, I would like to know the average age by total volume. If I provide the qty built per year, can I determine the average age of the lot (300) by total volume?
 Total built Year built 50 56 30 10 30 25 64 9 12 14 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980

Thanks

The median is greater than the mean 2009-08-14
From Shawna:
If the median is greater than the mean on a set of test scores, describe the situation.
Mean 2009-05-02
From debra:
a hot dog sales per week monday, 100 = tuesday,87 = wednesday, 95 = thursday, 125 = friday, 210 = saturday, 250 = sunday, 57 = what is the mean sales per day?
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.
4 times as many or 4 times more? 2009-02-02
From Jackie:
Given : Here are 3 squares and 4 sets of 3 circles.

I wonder it is right to write in the below manner to represent the following Conclusion that
can be made from the above given information:

1. There are 4 times as many circles as there are squares,

2. There are 4 times fewer square than circles;

3. There are 4 times more circles than squares.

4. ...
Jackie

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.
The average height of an attic 2008-09-12
From oliver:
I need to find out the average height of a specific volume/area.
a standard house shape side walls height 10m, height in centre of house 15m.
width 15m length 25m (the roof spans the width)
Within the house in the corner there is a (box shape) room which is 5m in height by 3m wide and 4 m long
How do i work out the average height of the space directly above the room (same floor area)?

Answered by Stephen La Rocque and Harley Weston.
What will be the resulting average? 2008-09-05
From jean:
the average of 9 is 54.if 84 and 90 are added to the set of numbers ,what will be the resulting average?
z-score 2008-07-02
From Candace:
If a normal-shaped distribution has a mean of 80 and a standard deviation of 15 what is the z-score for M=84 for a sample of n=25 scores. Is this sample mean in the middle 95% of the distribution?
The distribution of sample means 2008-07-02
From crystal:
A population forms a normal distribution with a mean of 75 and a standard deviation of 20. How do I sketch the distribution of sample means for samples of n= 100?
The mean, the median and the mode 2008-06-23
From Crystal:
Hi my name is Crystal,
My question is
under what circumstances will the mean, the median, and the mode all have the same value?

Answered by Stephen La Rocque and Harley Weston.
The mean and variance 2008-06-05
From Donny:
An investment will be worth \$1,000, \$2,000, or \$5,000 at the end of the year. The probabilities of these values are .25, .60, and .15, respectively. Determine the mean and variance of the worth of the investment.
The average rate of change 2008-03-29
From Tom:
For the function x/3x-1 find the average rate of change between the interval x=1 and x=5?
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

Average and mean 2008-03-17
From A student:
Mean and average are the same propeties of the set of elements, if there is average then why mathematician need the mean ?
Stacks of blocks 2008-02-07
From Tammy:
i need help for my son he is given 3 stacks of cubes. the 1rst stack has 3 the 2nd stack has 2 the 3rd stack has 4 the question is draw the stacks of cubes so they are arranged correctly to find the mean. what is the mean of the data?
Answered by Stephen La Rocque and Penny Nom.
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?

How old is the 11th person? 2007-12-08
From Jamie:
Ten people are in a room, and their mean age is 15. After another person enters the room, the mean age is now 18. How old is the person that walked in?
Answered by Jesse McLeod and Stephen La Rocque.
A decision based on data 2007-12-04
From manny:
You have administered a standardized test of manual dexterity to two groups of 10 semi skilled workers. One of these two groups of workers will be employed by you to work in a warehouse with many fragile items. The higher the manual dexterity of a worker the less likelihood that worker will break significant inventory. Because of a unique contract you must hire all 10 employees from one of the two groups and none of the employees from the other.

You must decide which group to choose. Choose at least two measures of central tendency and at least one measure of dispersion for each group and use those to make your choice. Be sure to justify your choice with at least one page of discussion and analysis.

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

Finding a geometric mean and taking its antilog 2007-08-27
From Jack:
Would like to know the basic geometric mean calculation. Also how would I take the antilog from this number?
The change in an average 2007-08-19
From farah:
the average height of a group of 25 students goes up by 2 cm when astudent of height 165 cm replaces a student from the group.what is the height of the boy who went out of the group?
What was the average? 2007-08-08
From Leroy:
A total of 50 juniors and seniors were given a math test. The 35 juniors attained an average score of 80 while the 15 seniors attained an average of 70. What was the average score for all 50 students who took the test?
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?

The "mode" of a set of numbers 2007-06-06
From Anthony's mom:
we have a graph: Kindergarten has 1, 1st has 5, 2nd has 4, 3rd has 3
is the mode "1st grade" because there are more children in that grade?

How to increase your average 2007-05-24
From Janna:
after taking 4 quizes your average is 71 out of 100. what must your average on the next 5 quizes be to increase your average to an 81 out of 100?
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.

Average 2007-05-06
From michelle:
the average of x and y is 20. If z = 5, what is the average of x, y, and z.
I have N data points in m-dimensional space 2007-04-29
From Sid:
Hi, Given below is the problem that I am facing: I have N data points in m-dimensional space. I know the mean euclidean distance of the points from one given point (say the origin). Now I wish to find the mean Euclidean distance of the N points from another given point. How can i do this without knowing the values of the N points and only knowing the 2 origin points and the mean distance from one of the origin points ?
Can you have median < mode < mean? 2007-04-11
From Kaliela:
Can the Median > mode > mean?
Can the Mean > Mode > Median?
I don't think either of these can occur but I'm unsure why?

Arithmetic means and geometric means 2007-04-04
From Dani:
Hi! I was just wondering why the arithmetic mean of sets of numbers is larger than the mean proportional of the same numbers? Thanks! Dani
A missing observation 2007-04-02
From destinee:
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.
The median 2006-09-26
From Sam:
How do you find the median in a group of numbers?
Answered by Stephen La Rocque and 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?
Divide the product of three consecutive positive integers by their mean 2006-03-12
From Sandy:
When I divided the product of three consecutive positive integers by their mean, I got 99. What is the smallest of the three numbers?
The meaning of numbers 2006-03-03
From John:
I'm having a philosophical debate on the meaning of numbers, equations, or the world of math in general. Would it be possible if you could help me by giving me a resource that talks about it or if you have your own opinion I would be most grateful.
Mean and average 2005-12-22
From Jerry:
This is just a question from a degreed engineer that has a "understanding" problem. please go to http://www.metrika.com/3medical/hemoglobin-m.html

At the end of the page they talk about "mean" vrs "average" there does appear to be a difference. What is it?

The Mean Value Theorem 2005-12-22
From Candace:
Verify that the function satisfies the hypotheses of the Mean Value Theorem on the given interval. Find all numbers "c" that satisfy the Mean Value Theorem. 11. f(x)=3x2 + 2x +5 [-1, 1]
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.

The golden ratio 2004-12-31
From Cristina:
let x represent the longer segment. to find the golden ratio, write a proportion such that the longer of the two segments is the geometric mean between the shorter segment and the entire segment.Use the quadratic Formula to solve the proportion for X. Find the value in both radical and decimal form.
AB/AP=AP/PB 2003-11-20
From James:
My name is James McBride. I'm having a difficult time with a pre calculus problem, which goes as follows: "show that AB/AP=AP/PB is equal to (1+5^1/2)/2 (one plus the sqaure root of five with the sum divided by two. I can't do the square root sign, sorry.) I have tried to solve for PB in terms of the other varialbles and then work the quadratic equation. THAT DOES NOT WORK!!!! I am befuddled. Please help me. I am a student of secondary level.
X bar 2003-11-04
From mary:
Remind me what this means:

```    _
X
```

Means 2003-10-28
From Abdu:

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

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

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

Answered by Andrei Volodin and Penny Nom.
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.

The golden ratio 2003-09-23
From Phillip:
The Golden Section can be made from an equilatereral triangle inscribed within a circle. The Golden Section is achieved by joining the mid points of two arms of the triangle to the circumference. I can prove this by erecting a perpendicular to the line outside the circle, but am interested to see how it can be proved from within the circle.
The mean house price 2003-09-10
From Carol:

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

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

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

E(X + Y) and V(X + Y) 2003-07-10
From Reuben:

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

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

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

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

Mean and median 2003-01-04
From Jan:

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

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

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

Mean, median and mode 2002-09-08
From Ramona:
1. How do you calculate the mean, median, and mode?

2. what are each of their definitions?

The mean distance travelled 2002-06-07
From A student:
If Rosalia travels 1000 km
Sheree travels 280 km
Daniel travels 50 km
Mica travels 200 km
Connor travels 500 km
Eric travels 250 km
Hillary travels 300 km

What was the mean distance travelled?

How do you arrive at the answer?

The average of two averages 2002-05-22
From RJ:
in a class with 22 students, the average garde on an exam was 68%, in another class with 32 students, the average grade on the same exam was 78%, what was the overall for the two classes? round your answers to the nearest whole number.
The Dugout, Don's Basement, Cd Corner,... 2002-04-30
From A student:
The Dugout, Don's Basement, Cd Corner, Harry's Deli, Bill's Software, Anne's Footwear, and Joanne's House cleaning.

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

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

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

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

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

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

Mathematical & conventional meaning of a word 2001-10-12
From A student:
What is the mathematical & conventional meaning of a word? Like the word Rational or Median.
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?
The Mean Value Theorem 2001-07-23
From Corrie:
I need to find if the mean value theorem exists. and if so, find all values c guaranteed by the theorem.

f(x) = |x2-25| on the interval [-10,0]

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?
The average value of a continuous function 2001-05-08
From Esther:
The average value of a continuous function y = f(x) on the interval [a,b] is given by ________________?
Lots of coins 2001-04-26
From A student:
I purchase 2 million coins at 9.75
I purchase 1 milion coins at 8
what is the formula to calculate my average cost?

A few problems 2001-04-22
From Carol:
Hello I am a College student trying get through my elmentry concepts class. I am also working with the middle and elementry school student with their work. I was given a few problems to work on and i am having a hard time explaining them to students. DO you think you can help with a coupld of these questions!
8, 4, 2, 18, 1, 9 2001-01-11
From Neyra:
Place each number below in one of the blanks to create the most meaningful and realistic story possible.
What is the difference between Mean and Average? 2000-12-13
From Julie:
What is the difference between Mean and Average? My thinking is the average, is the equal to the sum of all numbers divided by the number of numbers added together. But the mean, I think should be calculated by adding the largest and smallest numbers in the set and them dividing by 2. (which is the point where 1/2 the numbers are higher and 1/2 the numbers are lower)
Answered by Patrick Maidorn and Penny Nom.
Two more problems 2000-12-01
From Michael:
first question:
The mean of three test grades is 74. What must a fourth grade be to increase the mean to 78?

final question:
The product of two consecutive odd positive integers added to their sum is 119. What are these two integers?

Expected number 2000-11-02
From James:
1)There are 40,25,50 students in the traditional,reformed,and reformed traditional Calculas sections taught by three teachers. On one fine day the three sections congregate together to watch the NOVA video tape on Fermat's Last Theorem.

a) A student is randomly selected from he crowed of students.What is the expected number of students in the same section of this student?

****this question which i did not have any idea to do as follow for the part b
b) If one of the three teachers is selected at random, what is the expected number of students taught by is teacher?

Mr. Edgecomb's math exam 2000-09-17
From Rachel:
In Mr. Edgecomb's math class, 30 students took an exam on statistics. If the average passing grade was 84, the average failing grade was 60, and the overall average was 80, how many students passed the test?
Central Limit Theorem and Law of Large Numbers 2000-06-26
From Jonathan Yam:
The Central limit Theorem states that when sample size tends to infinity, the sample mean will be normally distributed. The Law of Large Number states that when sample size tends to infinity, the sample mean equals to population mean. Is the two statements contradictory?
Answered by Paul Betts and Harley Weston.
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?
Algebra 2000-01-18
From Candis:
I want to know what exactly is Algebra?
Not how to do it, or methods. Just what is it?

Absolute value 1999-12-29
From Alex Waller:
What are some practical applications for absolute value?
Fibonacci Numbers 1999-12-15
From Gary Nelb:
I'm doing a project on fibonacci numbers and I'm using different starting values and finding out if different starting values to see whether or not the ratios still get closer to phi. I was wondering, what numbers should I use. Should I use two of the same # like 2 and 2, or numbers like 1 and 2, or even something totally different.
From Kay:
1. Let a,b be contained in R, a
2. .
.
.

Mean, median and mode 1999-12-07
From J William Morning:
Using the data values 2,2,10,6,5, determine the median, mode and mean.
The sixth game 1999-11-16
From Stephanie Sprunger:
Janice scored 18,21,27,16,and 19 points in five basketball games. How many points must she score in the next game to raise her average to 22 points per game?
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?

Mean, median and mode 1999-11-06
From Rick:
I have five number places and the mean and median are both "0". The mode is greater than the mean. The sum of the absolute values of all of the numbers is 20. The smallest number is 4 less than the next smallest number. What are the five numbers. (negative integers can be used) All of the numbers are integers.
Prime dates 1999-03-25
From Jessica Brown:
I'm asking how do you figure out all the prime numbers in a year and, whats the average amount of prime numbers per week.
Answered by Jack LeSage and Penny Nom.
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!

The normal distribution. 1997-03-21
From Donna D.Hall:
I am looking for a proof for the normal distribution.

I suppose "proof" was not a good choice of words. What I am looking for is a way to "derive" the normal distribution in simple terms so that the most average teenager can see the logic. Can you help me?

Nombre d'or 2003-10-31
From Claude:

Comment démontrer que si a/b est égal au nombre d'or alors a+b/a est égal aussi au nombre d'or

Comment faut t il choisir a et b pour que le puzzle de lewis caroll soit réalisable? on sait déjà que les nombres 8 et 5 ainsi que 6 et 3 ne sont pas valables.