How do you determine the approx and exact expected real risk premiums on portfolio? Are there formulas?

QUESTION 3: Consider the following information about three stocks: a. If your portfolio is invested 40 percent each in A and B and 20 percent in C, what is the portfolio expected return? The variance? The standard deviation? b. If the expected T-bill rate is 3.80 percent, what is the expected risk premium on the portfolio? c. (no penalty for incorrect answer) If the expected inflation rate is 3.50 percent, what are the approximate and exact expected real returns on the portfolio? What are the aporoximate and exact expected real risk bremiums on the portfolio? QUESTION 3: Consider the following information about three stocks: a. If your portfolio is invested 40 percent each in A and B and 20 percent in C, what is the portfolio expected return? The variance? The standard deviation? b. If the expected T-bill rate is 3.80 percent, what is the expected risk premium on the portfolio? c. (no penalty for incorrect answer) If the expected inflation rate is 3.50 percent, what are the approximate and exact expected real returns on the portfolio? What are the aporoximate and exact expected real risk bremiums on the portfolio