Exercise 7: (8 points) Let U and V be two random variables Whose joint probability mass function is: P(U = n, V = m) = (m) 5m 8\" n W , 0Snm,>0 1. Find the probability mass functions of U and V. 2. Show that the random variables U and V U are independent. 3. Compute the expected value of the random variable 1 WHU