Idk why those three are wrong. Please help

Suppose we have the following Treasury bill returns and Inflation rates over an eight- year period: Year 1 2 3 4 5 Treasury bills 7.37% 8.07 5.95 5.15 5.53 772 10.64 12.18 Inflation 8.79% 12.42 702 4.94 6.78 9.10 13.37 12.60 a. Calculate the average return for Treasury bills and the average annual Inflation rate for this period. (Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.) b. Calculate the standard deviation of Treasury bill returns and inflation over this period. (Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.) c. What was the average real return for Treasury bills over this period? (A negative answer should be indicated by a minus sign. Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g.. 32.16.) correct Answer is complete but not entirely a. Treasury bills a. Inflation b. Treasury bills b. Inflation C. Average real return 7.83 96 9.39 % 2.32% 2.92 % 0.01 % x x