This is my little scratchpad for the variance.
$ Var(X) = E[(X-E[X])^2] $
$ Var(X) = E[(\sum_{i=1}{n} X_i - \sum_{i=1}{n}E[X_i])^2] $
$ = E[(\sum_{i=1}{n} (X_i - E[X_i]))^2] $
Still working on it.
