The standard deviation of the market-index portfolio is 15%. Stock A has a beta of 2.2 and a residual standard deviation of 25%. a. Calculate the total variance for an increase of .2 in its beta? a. Calculate the total variance for an increase of 3.84% in its residual standard deviation? b. An investor who currently holds the market-index portfolio decides to reduce the portfolio allocation to the market index to 90% and to invest 10% in stock A. Which of the following changes will have a greater impact on the portfolio's standard deviation? Increase of .2 in beta. Increase of 3.84% in residual standard deviation