6-75. You can earn thousands of dollars more from your mutual funds. The secret is to purchase no-load (no front-end commission) funds directly from companies specializing in this area. You can save 5.75% commission compared to “loaded” mutual funds when you buy no-load funds. That means you earn $4,000 more on a $23,000 investment over 10 years. In this situation, the average annual interest rate of the fund is most closely which answer below? (6.6)

(a) 6%

(b) 12%

(c) 15%

(d) 9%