Do bonds reduce the overall risk of an investment portfolio Let x be a random variable representing annual percent return for the Vanguard Total Stock Index all Stocks Let y be a random variable representing annual return for the Vanguard Balanced Index 60 stock and 40 bond For the past several years assume the following data Compute X A O 12 0 6 4879 O 5311 05033 4 39 27 24 15 33 26 27 12 25 17 15 4 12 5 24 6