answer for question c only. Thank you

Assume these are the stock market and Treasury bill returns for a 5 -year period: 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.) Answer is complete but not entirely correct. Complete this question by entering your answers in the tabs below. What was the standard deviation of the risk premium? (Ignore that the estimation is from a sample of data.) Note: Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places