Can you provide a thorough explanation? I am lost.

10 points) Suppose that you are interviewing for a job that has a total of n applicants. After our interview you conclude that the employers have a system that ranks the candidates rom 1 to n. (a) If X is the rank of a randomly selected candidate, what is the probability mass function of X? (3 points) b) Compute the expected rank of a randomly selected candidate. (3 points) (c) Compute the variance associated with this random variable. (4 points)