Suppose a discrete uniform random variable $X$ assumes only the values $C+L, C+2 L, \cdots, C+n L$, where $C, n$, and $L$ are constants. Show that
$$
E[X]=C+\frac{(n+1)}{2} L, E\left[X^2\right]=C^2+(n+1) L C+\frac{(n+1)(2 n+1)}{6} L^2,
$$
and
$$
\operatorname{Var}[X]=\frac{n^2-1}{12} L^2
$$