The answer is 22%, I need the solution for this.

17.20 Suppose a firm projects cash flows of $2.5 million, $3 million, and S4 million for years 1, 2, and 3, respectively, on an initial investment in Ecuador of $22 million. The firm projects a perpetuity of $5 million in years 4 and beyond. If the required return on this investment is 17%, how large does the probability of expropriation in year 5 have to be before the investment has a negative NPV? Expected compensation in the event of expropriation is $3 million