I need help understanding how to do this.

A pension fund manager is considering three mutual funds. The first is a stock fund, the second is a long-term government and corporate bond fund, and the third is a T-bill money market fund that yields a sure rate of 4.3%. The probability distributions of the risky funds are: Stock fund (S) Bond fund (B) Expected Return 13% 6% Standard Deviation 34% 27% The correlation between the fund returns is .0630. Suppose now that your portfolio must yield an expected return of 11% and be efficient, that is, on the best feasible CAL. a. What is the standard deviation of your portfolio? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Standard deviation 25.75 % b-1. What is the proportion invested in the T-bill fund? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Proportion invested in the T-bill fund % b-1. What is the proportion invested in the T-bill fund? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Proportion invested in the T-bill fund % b-2. What is the proportion invested in each of the two risky funds? (Do not round intermediate calculations. Round your answers to 2 decimal places.) Proportion Invested Stocks % Bonds %