问题如下：
There are two projects with the same conventional cash flow patterns and their information listed below:
To make the NPV of two projects equal, the cost of capital should be
选项：
A.smaller than 9%
B.between 9% and 12.06%
C.between 12.06% and 14.78%
解释：
B is correct. The question is more obvious to draw NPV profiles. When cost of capital is 9%, Project B is superior to Project A based on NPV rules (428>255). Due to 14.78%>12.06%, Project A is superior to Project B when cost of capital is larger than 12.06%. Therefore, the crossover rate of Project A and B is between 9% and 12.06%.
9% 的时候 B NPV 是 428？ A是 255？
