The standard deviation of the market-index portfolio is 20%. Stock A has a beta of 1.5 and

Question:

The standard deviation of the market-index is 20%. Stock A has a beta of 1.5 and a residual standard deviation of 30%.
a. What would make for a larger increase in the stock's variance: an increase of .15 in its beta or an increase of 3% (from 30% to 33%) in its residual standard deviation?
b. An investor who currently holds the market-index decides to reduce the allocation to the market index to 90% and to invest 10% in stock A. Which of the changes in (a) will have a greater impact on the portfolio's standard deviation?
Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...