Zenith Corp is planning to replace old machinery with a new one costing $400,000. The new machinery is expected to generate the following cash inflows:

• Year 1: $80,000
• Year 2: $90,000
• Year 3: $100,000
• Year 4: $110,000
• Year 5: $120,000

Requirements:

1. Determine the payback period.
2. Calculate the NPV at a 12% discount rate.
3. Calculate the IRR.
4. Assess the investment decision based on NPV and IRR.