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You've observed the following returns on Mary Ann Data Corporation's stock over the past five years: 38.50 percent, 20.50 percent. 23.50 percent, -25.50 percent, and 12.50 percent. a. What was the arithmetic average return on Mary Ann's stock over this flve-year period? (Do not round intermediate calculations. Round the final answer to 2 decimal places.) Arithmetic average return \% b-1. What was the variance of Mary Ann's returns over this period? (Do not round intermediate calculations. Round the final answer to 6 decimal places.) Variance b-2. What was the standard deviation? (Do not round intermediate calculations. Round the final answer to 2 decimal places.) Standard deviation \%