Here are the percentage returns on two stocks. Month January February March April May June July August Digital Cheese 15% -3 5 7 -4 3 -2 -8 Executive Fruit 7% 1 4 13 2 5 -3 -2 a-1. Calculate the monthly variance and standard deviation of each stock. (Do not round intermediate calculations. Round your answer to 1 decimal place.) Digital Cheese Executive Fruit 23.2 Variance 47.5 Standard deviation % 6.9 4.8 a-2. Which stock is the riskier if held on its own? Digital Cheese Executive Fruit b. Now calculate the variance and standard deviation of the returns on a portfolio that invests an equal amount each month in the two stocks. (Do not round intermediate calculations. Round your answer to 1 decimal place.) Variance Standard deviation %