For the cash flows shown, determine a) The number of possible values b) The i*value displayed by the IRR function c) The external rate of return using the MIRR method ifi,-18% per year and = 10% per year. Year Revenues, S 0 Costs, $ -6000 -30,000 -7000 -6000-12,000 0 4 25,00019,000400018,000