Based on current dividend yields and expected capital gains, the expected rates of return on portfolios A and B are 12% and 16%, respectively. The beta of A is 0.7, while that of Bis 1.4. The T-bill rate is currently 5%, whereas the expected rate of return of the S&P 500 index is 13%. The standard deviation of portfolio A is 12% annually, that of Bis 31%, and that of the S&P 500 index is 18%. Required: a. Calculate the alphas for the two portfolios. (Do not round intermediate calculations. Round your answers to 1 decimal place. Negative amount should be indicated by a minus sign.) Portfolio A Portfolio B % % b. If you could invest only in T-bills and one of these portfolios, which would you choose? Portfolio A Portfolio B