You've observed the following returns on Yamauchi Corporation's stock over the past five years: -28.2 percent, 15.8 percent, 34.6 percent, 3.4 percent, and 22.4 percent. a. What was the arithmetic average return on the stock over this five- year period? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) b. What was the variance of the returns over this period? (Do not round intermediate calculations and round your answer to 6 decimal places, e.g., 32.161616.) c. What was the standard deviation of the returns over this period? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.)