Answer:
4 years
Step-by-step explanation:
Payback period is the time in which a project returns back the initial investment in the form of net cash flow.
Initial Investment = $400,000
Annual increase in net Income = $100,000
Payback period = Initial Investment / Annual increase in net income
Payback period = $400,000 / $100,000
Payback period = 4 years
The initial cost of $400,000 will be paid back in only 4 years time by the equipment.