Ying Import has several bond issues outstanding, each making semiannual interest payments. The bonds are listed in the following table. If the corporate tax rate is 34%, what is the after-tax cost of debt?

Maturity 5 years 8 years 15 years 25 years # outstanding 40,000 35,000 55,000 50,000 Bond Coupon Rate 6% 75% 72% 4% YTM 4.5% 6% 8% 5.5% 4