Compute portfolio expected return and variance using the following information: w_A = 0.4: w_B = 0.6: E(R_A) = 10%: E(R_B) = 5%: sigma_A = 15%: sigma_B = 8%: rho_ab = 0.5 Demonstrate the diversification benefit using the following two stocks, by showing that any combinations of the two stocks provide superior risk-return tradeoff than the two individual stocks. Then explain in words what diversification benefit means. How this benefit varies with the level of rho_AB? E(R_A) = 5%: E(R_B) = 5%: sigma_A = 10%: sigma_B = 10%: rho_AB = 0.5 What is the most commonly used measure for exposure to systematic risk? Write out its mathematical expression and name each variable in the formula