Quantitative Problem: 5 years ago, Barton Industries issued 25-year noncallable, semiannual bonds with a $1,900 face value and a 10% coupon, semiannual payment ($95 payment every 6 months). The bonds currently sell for $845.87. If the firm's marginal tax rate is 40%, what is the firm's after-tax cost of debt? Round your answer to 2 decimal places. Do not round intermediate calculations. _________%