Assume these are the stock market and Treasury bill returns for a 5-year period: Stock Market T-Bill Return Return (%) (%) 32.40 0.06 0.06 2.30 0.06 13.60 22.10 0.26 2015 2016 2017 Required: a. What was the risk premium on common stock in each year? b. What was the average risk premium? c. What was the standard deviation of the risk premium? (Ignore that the estimation is from a sample of data.)