consider the following information on two stocks, cbs and nbc: stock expected return standard deviation cbs 0.06 0.03 nbc 0.04 0.03 the correlation of the returns of these stocks is -0.5. if 30 percent of a portfolio is invested in cbs and the rest in nbc, what is the standard deviation of portfolio returns? report your answer in decimal form rounded to the fourth decimal place (e.g., 0.1234).