Consider the joint PMF of X and Y is as follows X 1 2 3 1/20 2/20 2/20 0 3 2/20 4/20 1/20 2/200 0 1/20 3/20 1/20 0 1/20 0 0 (a) (10 points) Verify whether it is a valid joint PMF. (b) (10 points) Are X and Y independent? (c) (10 points) Find the marginal PMF of X and Y. (d) (20 points) Consider an event A = {X