Hugh has the choice between investing in a City of Heflin bond at 3.90 percent or investing in a Surething Inc. bond at 6.15 percent Assuming that both bonds have the same nontax characteristics and that Hugh has a 40 percent marginal tax rate, what interest rate does Surething Inc. need to offer to make Hugh indifferent between investing in the two bonds? (Round your answer to 2 decimal places.) Interest rate %