Darwin Dairy is thinking about buying a new bottling machine. The machine requires an initial investment of $75,000 and will have no salvage value at the end of its useful life. Darwin expects the machine to produce net annual cash flows of $15,500. In addition, it expects the machine to save $1,200 per year in lost product costs. If the project's estimated NPV is $17,431 and Darwin is using a 9% discount rate, what is the estimated life of the machine?
6 yrs--4.4859
7 yrs--5.033
8 yrs--5.5348
9 yrs--5.9952

a. 8 years
b. 7 years
c. 6 years
d. 9 years