Gomez Corporation is considering two alternative investment proposals with the following data: Proposal X Proposal Y Investment $ 850,000 $ 468,000 Useful life 8 years 8 years Estimated annual net cash inflows for 8 years $ 125,000 $ 78,000 Residual value $ 40,000 $ - Depreciation method Straight-line Straight-line Required rate of return 14% 10% How long is the payback period for Proposal Y