A company must choose between two machines. Machine A costs $100 000 and the annual operating expenses are estimated to be $40 000, while Machine B costs $160 000 and has estimated annual operating expenses of $25 000. Both machines have a 10-year life and will have a zero residual value.

A. The company has a required rate of return of 12 per cent per annum. Which machine should it purchase?

B. Rework the problem for an 8 per cent required rate of return.