问题如下：
Wilson Flannery is concerned that this project has multiple IRRs.
How many discount rates produce a zero NPV for this project?
选项：
A.One, a discount rate of 0 percent.
B.Two, discount rates of 0 percent and 32 percent.
C.Two, discount rates of 0 percent and 62 percent.
解释：
C is correct.
Discount rates of 0 percent and approximately 61.8 percent both give a zero NPV.
是要把I＝0，10，20，40，60，80，100. 一个个带入计算器算出哪个的NPV是最接近0的吗？有没有办法直接设NPV＝0，从而得出IRR的精确数呢？
