1. There are four stocks XI, X2, X3 and X4. Each share of Xi, X2, X3 and X4 has a payoff of 0 with probability 0.5 and 2 with probability 0.5. The payoffs of XI, X2, X3 and X4 are independent. (a) What is the mean and standard deviation of each stock? (b) Suppose you buy 1/2 share of Xi and X2, what is the mean and standard deviation of the portfolio? (c) Suppose you buy 1/3 share of XI, X2 and X3, what is the mean and standard deviation of the portfolio? (d Suppose you buy 1/4 share of XI, X2, X3 and X4, what is the mean and standard deviation of the portfolio