a PL Lumber stock is expected to return 20% in a booming economy, return 10% in a normal economy, and lose 2% in a recession. The probabilities of an economic boom, normal state, or recession are 7%, 89%, and 4%, respectively. The expected rate of return on this stock is and the standard deviation of the stock's return is M O a. 10.22%; 3.57% Ob 15.47%; 3-57% Oc 10.83%; 0.13% od 4.84%; 0.13%