2. (Annuity interest rate) Your folks just called and would like some advice from you. An insurance agent just called them and offered them the opportunity to purchase an annuity for $16,281.94 that will pay them $2,500 per year for 15 years. They don't have the slightest idea what return they would be making on their investment of $16,281.94. What rate of return would they be earning? The annual rate of return your folks would be earning on their investment is %. (Round to two decimal places.)