86. Let f (x) and g(y) be pdf s with corresponding cdf s F(x) and G(y), respectively. With c denoting a numerical constant satisfying , consider Show that f (x, y) satis es the conditions necessary to specify a joint pdf for two continuous rv s. What is the marginal pdf of the rst variable X? Of the second variable Y? For what values of c are X and Y independent?

If f (x) and g(y) are normal pdf s, is the joint distribution of X and Y bivariate normal?