A homeowner took out a 25-year, fixed-rate mortgage of $210,000. The mortgage was taken out 8 years ago at a rate of 7.1 percent. If the homeowner refinances, the charges will be $3,400. What is the highest interest rate at which it would be beneficial to refinance the mortgage? (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places.)

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