(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 $22,590.90 that will pay them $3,500 per year for 10 years. They don?t have the slightest idea what return they would be making on their investment of $22,590.90. 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.)