The stock is currently selling for $17.75 per share, and its noncallable $3,319.97 par value, 20-year, 1.70% bonds with semiannual payments are selling for $881.00. The beta is 1.29, the yield on a 6-month Treasury bill is 3.50%, and the yield on a 20-year Treasury bond is 5.50%. The required return on the stock market is 11.50%, but the market has had an average annual return of 14.50% during the past 5 years. The firm's tax rate is 40%. Refer to Exhibit 10.1. What is the best estimate of the after-tax cost of debt