A firm is considering a new inventory system that will cost $120,000. The system is expected to generate positive cash flows over the next four years in the amounts of $35,000 in year 1, $55,000 in year 2, $65,000 in year 3, and $40,000 in year 4. The firm's required rate of return is 9%. 1) What is the payback period of this project? 2) What is the net present value (NPV) of the project? _____ 3) Based on the information , what is the internal rate of return (IRR) of this project? 4) what is the profitability index (PI) of this project?