The probability distribution of a discrete random variable x is given by: p(x = −1) = 1 5 ,p(x = 0) = 2 5 and p(x = 1) = 2 5 (a) compute e[x]. (b) determine the probability distribution y = x 2 and use it to compute e[y ]. (c) determine e £ x 2 ¤ using the change-of-variable formula. (you should match your answer in part (b). (d) determine v ar (x).