XYZ has made a new investment. It invested $16,000 to purchase a new machine with an estimated life of 10 years. The following annual sales and expenses are projected (Ignore income taxes.): Sales $ 22,000 Expenses: Materials $ 10,000 Salaries 6,000 Depreciation 1,600 Net operating income $ 4,400 Assume cash flows occur uniformly throughout a year except for the initial investment. The payback period on the new machine is closest to: