You've observed the following returns on Doyscher Corporation's stock over the past five years: -27.3 percent, 15.2 percent, 33.4 percent, 3.1 percent, and 22.1 percent. Requirement 1: What was the arithmetic average return on the stock over this five-year period? Requirement 2: (a) What was the variance of the returns over this period? (b) What was the standard deviation of the returns over this period