Consider the following table for a period of six years: Year 1 Returns Large- U.S. Company Stocks Treasury Bills 15.89% 7.53% -26.83 8.11 37.47 6.11 24.17 6.27 - 7.64 5.57 6.81 8.00 2 3 5 6 a-1. Calculate the arithmetic average returns for large-company stocks and T-bills over this time period. (Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.) a-2. Calculate the standard deviation of the returns for large-company stocks and T-bills over this time period. (Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.) Large-company stocks T-bills % a-1. Arithmetic average return a-2. Standard deviation % % %