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. x: 12 0 24 16 19 30 28 -21 -21 -16 y: 14 -10 22 10 11 10 16 -11 -4 -2