PQR Corp plans to purchase equipment costing $350,000. The equipment has an expected life of 5 years with the following projected annual cash flows:

Year	Cash Flow ($)
1	90,000
2	80,000
3	70,000
4	60,000
5	50,000

There is no salvage value, and the company will depreciate the equipment using straight-line depreciation. The corporate tax rate is 20%. Required:

1. Calculate the Payback Period and ARR
2. Determine NPV and PI, with a discount rate of 7%
3. Calculate the IRR
4. Assess the effect of tax rate changes on the project’s viability