4. (10 Points) Let X and Y be two discrete random variables with ) = )' = {0, 1}. Arrange the values of px.y(x, y) as follows in terms of a matrix of size 2 x 2 MA Px, Y (0, 0) Px,y (0, 1) Px,y (1, 0) px,y (1, 1) Show that Cov(X, Y) = det (M). Is this this expression intuitive? Hint: A possible approach is based on using the relationshiop px,y (0, 0) + px,y (0, 1) + px,y (1, 0) + px,y (1, 1) = 1 at some step of the derivation