Find the expected value of X given other moments Given the variance $\mathbb{V}(X)=7$ and the expected square $\mathbb{E}(X^2)=16$, what is the expected value of $X$?

Hint: The variance of $X$ can be written as $\mathbb{V}(X) = \mathbb{E}(X^2) - \mathbb{E}(X)^2$.
