✔ 最佳答案
You can think in this way:
You get 2 plans on your hand, one is continuously using the old machine, but you need to repair the machine in year 11; the other is buy a new machine in year 5.
First of all, I suggest you to draw a time line of these two plans, one is for the old machine, the other is for the purchase of new machine.
You need to know that, if you keep using the old machine, the life of the old machine at the end when it expire is in year 12, since you get to repair the machine after year 10.
If you buy a new one, you will encounter a expense in year 5 and the machine will expire in year 11.
Tips:
1) You can separate in the two parts in your calculatoin, the continuously using the old machine, and the buying a new machine.
2) Calculate the depreciatoin respectively, note that the depreciation will change in year 11 in the old machine plan.
3) Calculate the Operating Cash Flow {( Revenue + Depreciation) [In this question only!!]}
4) Calculate the Discounted Cash Flow for each year using the operating cash flow in each year ( in this question only, since there are no NWC encounter)
Discounted Cash Flow = Operating Cash Flow x [1/(1 r)^t]
5) Calculate the Net Present Value (NPV) using the Discounted Cash Flow.
NPV = Expenses (-ve number) + Discounted Cash Flow each years.
6) Compare which plans will generate a higher NPV, and accept the project with the highest NPV
Conclusion:
I strongly encourage you to try it yourself, since you will learn from what you did.
The final answer you get, will be keep using the old machine rather than buy the new one.