Consider the following table for a period of six years: a-1. Calculate the arithmetic average returns for large-company stocks and T-bills over this time period. Note: Do not round intermediate calculations and enter your answers as a percent rounded to 2 deci a-2. Calculate the standard deviation of the returns for large-company stocks and T-bills over this time p Note: Do not round intermediate calculations and enter your answers as a percent rounded to 2 deci