The n candidates for a job have been ranked 1, 2, 3, . . . , n. Let X = the rank of a...

The n candidates for a job have been ranked 1, 2, 3, . . . , n. Let X = the rank of a randomly selected candidate, so that X has pmf

(this is called the discrete uniform distribution). Compute E(X) and V(X) using the shortcut formula. [Hint: The sum of the first n positive integers is n(n + 1) /2, whereas the sum of their squares is n(n + 1)(2n + 1)/6.]