Anne and Frank Smith each borrow $17,000 from their father. Anne and Mr. Smith have agreed that she will repay her loan in full by paying $5,000 in two years and $13,000 in four years. Frank prefers to make one lump payment of $20,000 to fully repay his loan. When should he make that payment so that he and his sister will each have the same effective interest rate? (Round your answer to two decimal places.) 4.89 X years