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8 articles trouvés pour ce sujet.
z-score 2008-07-02
Candace pose la question :
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?
Harley Weston lui répond.
The distribution of sample means 2008-07-02
crystal pose la question :
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?
Harley Weston lui répond.
Means of sample means 2005-10-12
Fareeha pose la question :
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.

Penny Nom lui répond.
Means 2003-10-28
Abdu pose la question :


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

Andrei Volodin and Penny Nom lui répond.
Statistics from grouped data 2003-10-09
Rebecca pose la question :

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.

Penny Nom lui répond.
Mean and median 2003-01-04
Jan pose la question :

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!

Penny Nom lui répond.
The average of two averages 2002-05-22
RJ pose la question :
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.
Leeanne Boehm lui répond.
Number conversions and averages 2002-02-03
A student pose la question :
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.

Penny Nom lui répond.



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