Heidi Company is considering the acquisition of a machine that costs $430,000. The machine is expected to have a useful life of 6 years, a negligible residual value, an annual net cash inflow of $106,000, and annual operating income of $81,210. The estimated cash payback period for the machine is (round to one decimal point)? a. 5.3 years b. 5.0 years O O O O C. 5.5 years d. 4.1 years