Let the joint probability density function of random variables X and Y be given by
f(x, y) = { 2 if 0 ≤ y ≤ x ≤ 1; 0 elsewhere.
(a) Calculate the marginal probability density functions of X and Y, respectively.
(b) Find E(X) and E(Y).
(c) Calculate P(X < 1/2), P(X < 2Y), and P(X = Y).