Suppose that a fund that tracks the S&P has a mean E(RM)-12% and standard deviation D-9% and suppose that the T-bill rate Rt= 3%. Answer the following questions about efficient portfolios: 3. What is the expected return and standard deviation of a portfolio that is exclusively invested in the risk-free asset? what is the expected return and standard deviation of a portfolio that has 50% of its wealth in the risk-free asset and 50% of its wealth invested in the S&P? What is the expected return and standard deviation of a portfolio that has 125% of its wealth in the S&P, financed by borrowing 25% of its wealth at the risk-free rate? a. b