$\text{Var}(X) = 4$ and $E(X) = 3$. What is $E(X^{2})$?

Explanation

1. 01

   $\text{Var}(X) = E(X^{2}) - [E(X)]^{2}$.

2. 02

   $E(X^{2}) = 4 + 9 = 13$.