if i could please get help on requirement 2! thanks!

Consider the following table for a period of six years. Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Returns Large-Company US Stocks Treasury Bills - 15.69% 7.49% -26.77 8.09 37.43 6.07 24.13 6.07 7.56 5.55 6.77 7.94 Requirement 1: Calculate the arithmetic average returns for large-company stocks and T-bills over this time period. Large company stock: 3.05 T-bills: 6.87 Requirement 2: Calculate the standard deviation of the returns for large-company stocks and T-bills over this time period Large company stock: T-bills