I have a problem with finding the variance (file attached in second post) - When I calculate the variance of this example i get it to 13.60, but in my textbook it says that the variance is 15.... What am I doing wrong?

Question

babynini · Answer

Sorry, I don't how how to do this. But I like your user name ;)

anonymous · Answer

That's okay... Haha and thx! I like yours too! ;)

babynini · Answer

Awe shucks haha

amistre64 · Answer

how many numbers are in the data set?

anonymous · Answer

10 :)

amistre64 · Answer

then you should have 10 'terms'in your summation, i only count 9

anonymous · Answer

Oh, that's right! Thank you!

amistre64 · Answer

what is:4.3^2/9 ?

anonymous · Answer

What part are you talking about right now?

amistre64 · Answer

you missed the  -4 part, so if we add that term in to what you have we should be good

anonymous · Answer

Oh yes, I found it! Thank you once again :)