Suppose that the index model for stocks A and B is estimated from excess returns with the following results: R_A = 1.60% + 0.70R_M + e_A R_B = -1.80% + 0.90R_M + e_{B M} = 22%; R-square_A = 0.20; R-square_B = 0.15 Assume you create portfolio P with investment proportions of 0.70 in A and 0.30 in B. a. What is the standard deviation of the portfolio? (Do not round your intermediate calculations. Round your answer to 2 decimal places.) b. What is the beta of your portfolio? (Do not round your intermediate calculations. Round your answer to 2 decimal places.) c. What is the firm-specific variance of your portfolio? (Do not round your intermediate calculations. Round your answer to 4 decimal places.)