6. Let the joint probability distribution function of two discrete random variables X and Y defined by fx, x (2, y) = xty x = 1, 2, y = 1, 2, 3, 4. 32 Find (a) fx(x), fy(y) the marginal distribution of X and Y. (b) P(X + Y = 3). (c) P(Y = 2X). (d) Are X and Y independent