Here are the percentage returns on two stocks. Digital Cheese 15% Executive Fruit 7% Month January February March April May June July August b c w vurub W PWN a-1. Calculate the monthly variance and standard deviation of each stock. (Do not round intermediate calculations. Round your answers to 1 decimal places.) Digital Cheese Executive Fruit Variance Standard deviation % IIIIIIIIIIIIIIIIIIIIIIIIIIIIIII a-2. Which stock is the riskier if held on its own? O Digital Cheese O 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 %