What is th best portfolio mix of risk per unit of return? We need the equation for it as well.

chapter 4 expected return and the standard deviation when varying percentages of Reese's investment is allocated between A and B. Return 40%A6%B 100B Standard Deviation Security A 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Security B 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Return 11.00% 10.50% 10.00% 9.50% 9.00% 8.50% 8.00% 7.50% 7.00% 6.50% 6.00% 20.00% 18.03% 16.12% 14.32% 12.65% 11.18% 10.00% 9.22% 8.94% 9.22% 10.00% Notice that if Reese were to invest 80% in B and 20% in A, her return would increase from 6.00% to 7.00%, while her risk would decrease to 8.94% from 10%. By making this change, she is able to increase her return and decrease her portfolio risk. If she were to invest 60% in B and 40% in A, her return would increase from 6.00% to 8.00%, while her risk would remain the same. Clearly, the 60/40 portfolio is a more efficient portfolio than the 100% invested in B. The phrase, "more efficient," means a higher return for the given level of risk Portfolio Risk and Return 137