The joint probability density function (pdf) of X and Y is given by f(x,y) = 2, 0 <= x <= y <= 1. (a) Find f_X(x) and f_Y(y), the marginal pdfs of X and Y, respectively. (b) Are X and Y independent? Explain why or why not. (c) Find P(2X < Y). (d) Find the conditional variance of X given Y = 1/4, i.e. V(X|Y = 1/4).