问题如下：
Assume a project has net present value of $500 and IRR=8.5%. If all cash flows involved in the project, for example the initial investment and the cash inflows, are doubled, the project will have:
选项：
A.a net present value between $500 and $1,000, and IRR larger than 8.5%
B.a net present value of $1,000 and IRR equal to 8.5%
C.a net present value of $500 and IRR equal to 8.5%
解释：
B is correct. NPV is the present value of the future cash inflows less the initial investment. If both cash inflows and initial investment are doubles, NPV will double. IRR is the discount rate that makes present value of the future cash inflows equal the initial investment. The percentage profitability does not change, therefore IRR will remain the same.
为什么IRR不变那？
