Ying Import has several bond issues outstanding, each making semiannual interest payments. The bonds are listed in the table below. Bond Coupon Rate Price Quote Maturity Face Value 1 8.90 % 105.4 3 years $ 24,000,000 2 6.60 95.0 6 years 44,000,000 3 8.60 104.2 13.5 years 49,000,000 4 9.10 106.1 23 years 64,000,000 If the corporate tax rate is 35 percent, what is the aftertax cost of the companys debt? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.)

I've been able to calculate weights and am having difficulty finding # of periods needed to fill the rate function in excel:

Weight

1: 25296000--.135958

2: 41800000-- .224661

3: 51058000-- .27442

4: 67904000-- .364961

Total Market Value: 186058000