The same result can be obtained from tables of Appendix 8. In this case, PWF = Cs FLC =15,100/(0.63 x 185 x 9) = 14.395. This is very close to the first value (d =0) of the column for i = 9% for n = 10 (PWF = 14.487). Interpolation can be used to get a more correct answer, but the exact result can be obtained with more accuracy with Eq. (12.26)