iRobot Company is analyzing two machines to determine which one it should purchase. Whichever machine is purchased will be replaced at the end of its useful life. The company requires a 14 percent rate of return and uses straight-line depreciation to a zero book value over the life of the machine. Machine A has a cost of $487,000, annual operating costs of $29,000, and a 6-year life. Machine B costs $315,000, has annual operating costs of $51,200, and a 4-year life. The firm currently pays no taxes. Which machine should be purchased and why