An anticipated purchase of equipment for $500,000, with a useful life of 8 years and no residual value, is expected to yield the following annual net incomes and net cash flows:

Year	Net Income	Net Cash Flow
1	$60,000	$120,000
2	50,000	110,000
3	50,000	110,000
4	40,000	100,000
5	40,000	60,000
6	40,000	60,000
7	40,000	60,000
8	40,000	60,000

What is the cash payback period?

5 years

4 years

3 years