Here are the returns on two stocks. Digital Cheese Executive Fruit January +13 +6 February -2 +1 March +4 +4 April +6 +14 May -3 +2 June +2 +5 July -1 -2 August -7 -1 Required: a-1. Calculate the variance and standard deviation of each stock. a-2. Which stock is riskier if held on its own? b. Now calculate the returns in each month of a portfolio that invests an equal amount each month in the two stocks. c. Is the variance more or less than halfway between the variance of the two individual stocks?