Stacy made a deposit of $8,500.00 into an account. After ten years, the account had earned $5,525.00 in interest. What simple interest rate did the account earn?

6.5% because it is over a 10 year period you divide 8,500 by 10

So I'm going to guess this is what they mean by simple interest. The amount gained in interest, what percent of that is it of the total? That's just (5525/8500) * 100 to get the percentage. That's 65%. However spread out over 10 years means you need to divide that by 10 to get 6.5%.