Suppose you are told that the average return on investment for a particular class of investments was 7.8% with a standard deviation of 2.3. Furthermore, the histogram of the distribution of returns is approximately bell-shaped. We would expect that 95 percent of all of these investments had a return between what two values? a. 5.5% and 10.1% b. 0% and 15% c. 3.2% and 12.4% d. 0.9% and 14.7% e. 3.2% and 14.7%