If the joint probability density function of X and Y is given by f(x,y) = 2/3(x + 2y) for 0 < x < 1, 0 < y < 1, and 0 elsewhere. Find the marginal distribution of X. Find the marginal distribution of Y. Find the conditional mean of X given Y = 1/2. Find the conditional variance of X given Y = 1/2.