(IRR calculation) Your investment advisor has offered you an investment that will provide you with a single cash flow of $11,500 at the end of 18 years if you make an annual payment of $300 per year in the interim period. Specifically, the annual payments begin immediately and extend through the end of year 17. You then receive the $11,500 at the end of year 18. Find the internal rate of return on this investment. This investment's internal rate of return is %. (Round to two decimal places.)