Let X and Y be discrete i.i.d random variables with geometric probability mass function with parameters with the parameter q as follows (p + q = 1): P(x = k) = pq*, P(y = i) = pq', k,i = 0, 1, 2, ... (1) a. Define Z = max(X, Y). (2) Find p.m.f. of Z. b. Define Z = min(X, Y), W = X-Y (3) Find the joint p.m.f of Z, W