Explain why, if two mutually exclusive projects are being compared, the project that generates most of its cash flows in the beginning of its life might have the higher ranking under the NV criterion if the required rate of return is high, whereas the project that generates most of its cash flows toward the end of its life might be deemed better if the required rate of return is low. Would changes in the firms required rate of return ever cause a change in the IRR ranking of two such projects? Explain.