Consider the following table for a period of six years: Year 1 2 3 4 Returns Large- U.S. Company Stocks Treasury Bills 16.49% 7.65% - 27.01 8.17 37.59 6.23 24.29 6.87 7.88 5.63 6.93 8.18 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 % % 96 a-2 Standard deviation