Seth Fitch owns a small retail ice cream parlor. He is considering expanding the business and has identified an attractive investment opportunity. The investment involves purchasing a machine that would enable Mr. Fitch to offer frozen yogurt to customers. The machine would cost $7,920 and has an expected useful life of three years with no salvage value. Additional annual cash revenues and cash operating expenses associated with selling yogurt are expected to be $6,100 and $820, respectively. Required Determine the payback period for the investment. (Round your answer to 2 decimal places.) Determine the investment's annual incremental net income assuming straightline depreciation for the machine. Determine the unadjusted rate of return for the investment.