Unbiased sample variance question
I have what should be a very simple problem, however I'm sure the answer im getting is wrong =(
Calculate the unbiased sample variance of the following numbers (weights of bags of sugar, not that it makes a difference).
1013, 997, 1013, 1013, 1004, 985, 991, 997
I know the formula is
( 1 / (n-1) ) * Sum((xi-mean)^2)
So i plug in the numbers, and i get
mean = 1001.625
For Sum((xi-mean)^2) I get 825.875 (wrong?)
Then plugging in the values I end up with a variance of 117.98 which is clearly wrong, I think it should be 10.86ish.
Can anyone point out my (probably trivial) error please?
Thanks in advance.