and the other positive. root can be used for the IRR-with results The modified internal rate of return (M that are external to the project. The numb that the MIRR can be found. PROBLEMS 7A-3 Unless the problem asks a different question or pro- vides different data: (1) determine how many roots are possible and (2) graph the PW versus the interest rate to see whether multiple roots occur. If the root is a unique IRR, it is the project's rate of return. If there are multiple roots, then use an external investing rate of 12% and an external borrowing rate of 6%. Compute and use the MIRR as the project's rate of return