Given the following data: $102, 40, 27, 108, 124, 113, 143, 100, 115, 128$
If $\sum_{i=1}^{10} X^2 = 112600$, what is the sample variance?
The correct answer is $1400$.
However, when I tried calculating in Excel, I got an answer of $34,047,397$.
I took each $X$ value, squared it, subtracted the mean of $112,600$, took the difference and squared that, summed it, and then divided by $10$ terms.
I also tried using a chi-squared variance of $2v=20$, but that didn't match the answer either.
Can someone please point me in the right direction?
VAR.S
to calculate the sample variance. Alternatively, you could make use of the following relationship: $\mathrm{Var}(X)=\mathrm{E}(X^2)-\mathrm{E}(X)^2$. $\endgroup$ – COOLSerdash Feb 16 '14 at 9:40