A firm is considering the purchase of one of two machines. The first (machine A), costing 4000, is expected to bring in revenues of 2000, 2500 and 1500 respectively in the 3 years for which it will be operative; while the second (machine B), which costs 3900, will produce revenues of 1500, 2500 and 2000, and has the same lifetime. Neither machine will have any appreciable scrap value at the end of its life. Assuming a discount rate of 8%, compare and contrast different methods (Profit, Payback, ARR, NPV, and IRR) for evaluating which machine should be purchased. (Hint to calculating IRRs: a discount rate of 25% gave NPVs of -32 and -76 for machines A and B respectively.)