9. Implied interest rate and period Consider the case of the following annuities, and the need to compute either their expected rate of return or duration. Joshua inherited an annuity worth $6,830.77 from his uncle. The annuity will pay him eight equal payments of $1,100 at the end of each year. The annuity fund is offering a return of Joshua's friend, Willie, has hired a financial planner for advice on retirement. Considering Willie's current expenses and expected future lifestyle changes, the financial planner has stated that once Willie crosses a threshold of $1,387,311 in savings, he will have enough money for retirement. Willie has nothing saved for his retirement yet, so he plans to start depositing $25,000 in a retirement fund at a fixed rate of 6.00% at the end of each year. It will take for Willie to reach his retirement goal