You've observed the following returns on Regina Computer's stock over the past five years: 19%, -13%, 16%, 21%, and 10%. a. What was the arithmetic average return on Regina's stock over this five-year period? (Round the final answer to 1 decimal place.) Average return % b-1. What was the variance of Regina's returns over this period? (Do not round intermediate calculations. Round the final answer to 5 decimal places.) Variance b-2. What was the standard deviation of Regina's returns over this period? (Do not round intermediate calculations. Round the final answer to 1 decimal place.) Standard deviation %