How did I get the answers for Processing Mill wrong? I multiplied the numbers from every year with the compound interest every year at 10% plus I thought that the residual value would have to be added with the initial investment for the amount to be invested.

Net Present Value-Unequal Lives Bunker Hill Mining Company has two competing proposals: a processing mill and an electric shovel. Both pieces of equipment have an initial investment of $501,956. The net cash flows estimated for the two proposals are as follows: Net Cash Flow Year Processing Mill Electric Shovel 1 $153,000 $191,000 2 136,000 177,000 3 136,000 164,000 4 109,000 168,000 5 83,000 6 69,000 7 60,000 8 60,000 The estimated residual value of the processing mill at the end of Year 4 is $190,000. Present Value of $1 at Compound Interest Year 6% 10% 12% 15% 20% 1 0.943 0.909 0.893 0.870 0.833 2 0.890 0.826 0.797 0.756 0.694 3 0.840 0.751 0.712 0.658 0.579 4 0.792 0.683 0.636 0.572 0.482 5 0.747 0.621 0.567 0.497 0.402 5 83,000 6 69,000 7 60,000 8 60,000 The estimated residual value of the processing mill at the end of Year 4 is $190,000. Present Value of $1 at Compound Interest Year 6% 10% 12% 15% 20% 1 0.943 0.909 0.893 0.870 0.833 2 0.890 0.826 0.797 0.756 0.694 3 0.840 0.751 0.712 0.658 0.579 4 0.792 0.683 0.636 0.572 0.482 5 0.747 0.621 0.567 0.497 0.402 6 0.705 0.564 0.507 0.432 0.335 7 0.665 0.513 0.452 0.376 0.279 8 0.627 0.467 0.404 0.327 0.233 9 0.592 0.424 0.361 0.284 0.194 10 0.558 0.386 0.322 0.247 0.162 Determine which equipment should be favored, comparing the net present values of the two proposals and assuming a minimum rate of return of 10%. Use the present value table appearing above. Processing Mill Electric Shovel Present value of net cash flow total $ 546,268 x $ 557,729 Determine which equipment should be favored, comparing the net present values of the two proposals and assuming a minimum rate of return of 10%. Use the present value table appearing above. Processing Mill Electric Shovel Present value of net cash flow total 546,268 x 557,729 Less amount to be invested 691,956 x 501,956 Net present value -145,688 x 55,773 Which project should be favored? Processing Mill Feedback Check My Work For each proposal, multiply the present value factor for each year (Refer Exhibit 2 in the text) by that year's net cash flow. Use the residual value of the Processing Mill to equate the useful lives (Refer Exhibit 2 in the text). Subtract the amount to be invested from the total present value of the net cash flow