Statistics Help

Question

A test problem states:

Find the standard deviation of this set of numbers

3 , 7 , 4 , 6 , 5 , 9 , 7 , 4

                      The answers of four students are:

                      A:   4.48         B:   0.261       C:   1.99         D:   10.4

One student is correct – which one?

Write down a data set below (n = 6) that has a mean of 5 and a standard deviation of 0.

Answer 1

mean = 45/8 = 5.525

find deviations from the mean

3 2.525

4 1.525 2 4's

5 0.525

6 .475

7 1.475 2 7's

9 3.475

square each

sum them

divide by 7

then take the square root

rough guess is c

a looks more like the variance

b and d too small and big

5 5 5 5 5 5 is a data set of 6 which has mean 5 and 0 standard deviation