January February March April May June July August por para 15% -5 6 7 --6 4 -5 -8 9% 1 4 15 2 4 -5 a-1. Calculate the monthly variance and standard deviation of each stock. (Do not round intermediate calculations. Round your answers to 1 decimal places.) Executive Fruit Digital Cheese 0.1 Variance 0.3 Standard deviation % 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 answers to 1 decimal places.) Variance Standard deviation %