Q:

Excel Sigma Summation - Quadratic Expression

I am trying to make a Variance summation in Excel. I know there is a function for it, but I want to use the Sigma summation:

I found some threads, but all of them assume a non-quadratic expression. This one for example: Sigma or Summation function in Excel
I have the given data in Excel, and just need to put it together in this Sigma Summation. How would I write the function to make it work?

A:

Found the answer myself after playing with the expression I got from the other thread that I mentioned. The problem was that I did not know how to make it squared, because I did not see where the variable was exactly.
In the end, this function did it for me. The X variable was entered as data starting from E31:E35 (which was a small example to be able to control the answer). The variance was then calculated.
=SUMPRODUCT(SUMSQ(E31:E35-D37))/(C34-1)

The key to this was to understand that the SUMPRODUCT function returns the sum of the range.

