Find the average monthly risk premium earned by each of the four stocks over this period of time and the Sharpe Ratio for each of the four stocks? (Hint: A risk premium is defined as return of an investment in excess of risk-free rate and Sharpe ratio is defined as risk premium of an investment divided by the standard deviation of the investment. It is well-known that T-bill can be considered a proxy for risk-free investment. You have calculated average monthly return for each stock and that for the T-bill investment. So, you have all the information required for the calculation of average monthly risk premium for each of the four stocks.)

I have a covariance matrix and a correlation matrix in an excel document with all the data but I need help finding the above question.