If var (X) = 50, var (X -f- F) = 80, and var (X — F) = 40, find var (F)

and cov (X, Y).

44.Suppose that X and F are continuous random variables with joint density function given by the rule k(x + y)

fix, y) = •

for 0 < x < 2, 0 < y < 2, 0 elsewhere.