3. Consider three investors A, B, and C. Investor A's risk aversion coefcient AA = 5, B's risk aversion coefcient AB = 4.2, and C's risk aversion coefcient A0 = 3. There is one risky asset, whose expected return is 10 percent and standard deviation is 12 percent. Suppose the riskfree borrowing rate is 4 percent and the riskfree saving rate is 3 percent. The objective of the three investors is to maximize E033) 0.005A103, where E(rc) and 03 are the expected return and the variance of an investor's portfolio and 2' = A, B, C. (a) What is investor A's optimal portfolio weight in the risky asset? (b) What is investor B's optimal portfolio weight in the risky asset? (c) What is investor C's optimal portfolio weight in the risky asset