You are considering investing in a new gold mine in South Africa. Gold in South Africa is buried very deep, so the mine will require an initial investment of $260 million. Once this investment is made, the mine is expected to produce revenues of $28 million per year for the next 20 years. It will cost $11 million per year to operate the mine. After 20 years, the gold will be depleted. The mine must then be stabilized on an ongoing basis, which will cost $4.8 million per year in perpetuity. Calculate the IRR of this investment. (Hint: Plot the NPV as a function of the discount rate.)