{9, 7, 13, 24, 32, 45, 47}

First you have to find the mean
The mean is
9+7+13+24+32+45+47=177/7=25.2857=25.29
Find the standard deviation for the given data. Round your answer to one more decimal place than the original data.
{9, 7, 13, 24, 32, 45, 47}

(25.29-9)^2=16.29^2=265.36
(25.29-7)^2=18.29^2=334.52
(25.29-13)^2=12.29^2=151.04
(25.29-24)^2=1.29^2=1.66
(25.29-45)^2= -19.71^2=388.48
(25.29-47)^2= -21.41^2=458.39

1599.45
Sqrt 39.99
My answer isn't matching the possible choices

1 answer

your mean is correct.

(25.29-9)^2=16.29^2=265.36
(25.29-7)^2=18.29^2=334.52
(25.29-13)^2=12.29^2=151.04
(25.29-24)^2=1.29^2=1.66
(25.29-45)^2= -19.71^2=388.48
(25.29-47)^2= -21.41^2=458.39
Your second moment about the mean is correct.
Now, standard deviation. I would divide that sum by n=7 (or in real life, n-1) then take the square root.
I get about 16

http://hubpages.com/hub/deviation