Kirk Van​ Houten, who has been married for 24 ​years, would like to buy his wife an expensive diamond ring with a platinum setting on their 30​-year wedding anniversary. Assume that the cost of the ring will be ​$10,426 in 6 years. Kirk currently has ​$4,750 to invest. What annual rate of return must Kirk earn on his investment to accumulate enough money to pay for the​ ring?