The internal rate of retum method is used by Testerman Construction Co, in analyzing a capital expenditure proposal that involves an investment of $62,400 and annual net cash flows of $15,000 for each of the seven years of its useful site Present Value of an Annuity of $1 at Compound Interest Year 6% 10% 12% 15% 20% 1 0.943 0.909 0.893 0.870 0.833 2 1.833 1.736 1.690 1.626 1.528 3 2.673 2.487 2.402 2.283 2.106 4 3.465 3.170 3.037 2.855 2.589 S 4.212 3.791 3.605 3.353 2.991 6 4.917 4.355 4.111 3.785 3.326 7 5.582 4.868 4.564 4,160 3.605 B 6.210 5.335 4.968 4.487 3.837 9 6.802 5.759 5.328 4.772 10 7.360 6.145 5.650 5.019 4.031 4.192 a. Determine a present value factor for an annuity of $1 which can be used in determining the internal rate of return. If required, round your answer to three decimal places. b. Using the factor determined in part (a) and the present value of an annuity of $1 table above, determine the internal rate of return for the proposal