8. A stock has an average return of 12.8 percent and a standard deviation of 27.2 percent. What range of returns would you expect to see approximately two-thirds of the time? a. -41.6 to +672 percent b. -32.8 to +58.4 percent c. -14.4 to +40.0 percent d. -7.2 to +24.4 percent e. -0.8 to +26.4 percent