Bill OBrien would like to take his wife, Mary, on a trip three years from now to Europe to celebrate their 40th anniversary. He has just received a $24,000 inheritance from an uncle and intends to invest it for the trip. Bill estimates the trip will cost $33,480. (FV of $1, PV of $1, FVA of $1, PVA of $1, FVAD of $1 and PVAD of $1) (Use appropriate factor(s) from the tables provided.) What interest rate, compounded annually, must Bill earn to accumulate enough to pay for the trip?