please solve for part B by showing your work/formulas on excel and thank you.

Expected Monthly Return Expected Monthly Return PG Microsoft BAC Exxon 0.010848 0.014854 0.011589 0.012043 Variance Variance PG Microsoft BAC Exxon 0.004478 0.012820 0.005611 0.002820 Covariance Cov(PG, Microsoft) Cov(PG, BAC) Cov(PG, Exxon) Cov(Microsoft, BAC) Cox(Microsoft, Exxon) Cov(BAC, Exxon) -0.000649 0.000683 0.000433 0.001681 0.000804 0.000757 For this assignment, please use excel file group_assignment_1_portfolios.xls posted on blackboard under the folder of Excel Files. The file contains the monthly returns of 4 stocks over the 10-year period -- January 1997 -- December 2006. In this file, the expected monthly return for each stock is calculated using excel function AVERAGE 0, for each stock, the variance of monthly returns is calculated using Excel function VAR (, and the covariance between the returns of each pair of stocks is calculated using Excel function COVAR (). Assume that the yearly risk-free rate is 2% (A monthly risk-free rate of 0.001652). we assume that investors invest in the risk-free asset and 4 risky assets (PG, Microsoft, BAC, and Exxon). 6) Find the optimal investment portfolio in the risky assets. What are the mean and s. d. of the returns of this portfolio