15.4 The managers of United Medtronics are evaluating the following four projects for the coming budget period. The firms corporate cost of capital is 14 percent. Project Cost IRR A $15,000 17% B 15,000 16 C 12,000 15 D 20,000 13 a. What is the firms optimal capital budget? b. Now, suppose Medtronicss managers want to consider differential risk in the capital budgeting process. Project A has average risk, B has below-average risk, C has above-average risk, and D has average risk. What is the firms optimal capital budget when differential risk is considered? (Hint: The firms managers lower the IRR of high-risk projects by 3 percentage points and raise the IRR of low-risk projects by the same amount.)