Please help!! Financial Management

要計Present value,你要有每一年的net cash flow及discount rate，不是interest rate.

例如，一個項目要付出$10,000，第一年會有$5,000淨現金收入，第二年會有$4,000現金收入，最後一年會有$3,000現金收入，之後就沒有了。而discount rate = 10%

Net Present Value=
-10,000 + 5,000/1.1 + 4,000/1.1^2 + 3,000/1.1^3
= -10,000 + 4545.45 + 3305.79 + 2,253.94
= 105.18

注意，accounting profit 會
= -10000 + 5000 + 4000 + 3000
= 2,000

以下提供discount rate 的解釋作參考：
The discount rate
Choosing an appropriate discount rate is crucial to the NPV calculation. A good practice of choosing the discount rate is to decide the rate which the capital needed for the project could return if invested in an alternative venture. If, for example, the capital required for Project A can earn five percent elsewhere, use this discount rate in the NPV calculation to allow a direct comparison to be made between Project A and the alternative. Obviously, NPV value obtained using variable discount rates with the years of the investment duration is more reflecting to the real situation than that calculated from a constant discount rate for the entire investment duration. Refer to the tutorial article written by Samuel Baker for more detailed relationship between the NPV value and the discount rate.
For some professional investors, their investment funds are committed to target a specified rate of return. In such cases, that rate of return should be selected as the discount rate for the NPV calculation. In this way, a direct comparison can be made between the profitability of the project and the desired rate of return.
The rate used to discount future cash flows to their present values is a key input of this process. Most firms have a well defined policy regarding their capital structure. So the weighted average cost of capital (after tax) is appropriate for use with all projects. Alternately, higher discount rates can be used for more risky projects. Another method is to apply higher discount rates to cash flows occurring further along the time span, to reflect the yield curve premium for long-term debt.