The stock is currently selling for $15.25 per share, and its noncallable $1,000.00 par value, 20 -year, 9.00% bonds with semiannual payments are selling for $930.41. The beta is 1.22, 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 25%. Refer to Exhibit 10.1. What is the best estimate of the after-tax cost of debt? 5.23% 6.1796 6.48% 73596