Here are the percentage returns on two stocks. a-1. Calculate the monthly variance and standard deviation of each stock. (Do not round intermediate calculations. Round your answers to 1 decimal places.) 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.)