GHI Industries is considering investing in a new plant. The plant's cost is AUD 400,000, with an expected useful life of 8 years and a residual value of AUD 40,000. Depreciation is on a straight-line basis. The company's cost of capital is 11%. The expected cash inflows and profits are:

Year	Cash Inflow	Profit
1	$70,000	$5,000
2	$75,000	$10,000
3	$80,000	$15,000
4	$85,000	$20,000
5	$90,000	$25,000
6	$95,000	$30,000
7	$100,000	$35,000
8	$105,000	$40,000

Tasks: a) Define relevant costs in the context of capital investment. b) Differentiate between the payback period and the internal rate of return (IRR). c) Using the information provided, calculate: i) The payback period. ii) The NPV of the new plant. iii) Provide a recommendation on whether GHI Industries should invest in the new plant.