4. Consider two efficient portfolios which combine the portfolio of risky assets and the risk- free asset and have the following characteristics: Portfolio P2 Epf P1 12.8% 6% 21.9% opf 13% a. write the equation of the efficient frontier and draw it b. consider portfolio P3 on the efficient frontier composed only of risky assets. The standard deviation of this portfolio is 10%. What is the expected return? c. Explain how to construct a portfolio P4 with an expected return of 16%