Do bonds reduce the overall risk of an investment portfolio Let x be a random variable representing annual percent return for Vanguard Total Stock Index all stocks Let y be a random variable representing annual return for Vanguard Balanced Index 60 stock and 40 bond For the past several years we have the following data x 12 0 35 20 30 24 23 12 12 22 y 10 2 30 12 21 17 15 2 a Compute Ex Ex LAUSE SALT Compute Ex Ex Compute y Ey y S Compute Ey Ey S b Use the results of part a to compute the sample mean variance and standard deviation for x Round your answers to four decimal places x s 3 12 Use the results of part a to compute the sample mean variance and standard deviation for y Round your answers to four decimal places y s c Compute a 75 Chebyshev interval around the mean for x values Enter your answer in the form lower limit t Include the word to Round your numerical values to two decimal places Compute a 75 Chebyshev interval around the mean for y values Enter your answer in the form lower limit to upper limit Include the word to Round your numerical values to two decimal places Use the intervals to compare the two funds O 75 of the returns for the balanced fund fall within a narrower range than those of the stock fund 75 of the returns for the stock fund fall within a narrower range than those of the balanced fund O 25 of the returns for the balanced fund fall within a narrower range than those of the stock fund 25 of the returns for the stock fund fall within a wider range than those of the balanced fund d Compute the coefficient of variation in percent for fund x Round your answer to the nearest whole number Compute the coefficient of variation in percent for fund y Round your answer to the nearest whole number upper limit Use the coefficients of variation to compare the two funds For each unit of return the stock fund has lower risk For each unit of return the balanced fund has lower risk For each unit of return the funds have equal risk If s represents risks and x represents expected return then s x can be thought of as a measure of risk per unit of expected