不对啊为什么我用5m来表示直接代公式算出来是0.71选A？？？？

问题如下：

PZ company need to borrow $5 millions for one month through commercial paper at 8%, the dealer’s commission is 0.2% and the backup line cost is 0.25%, please calculate the borrowing cost:

选项：

0.71%

8.5%

6.7%

解释：

B is correct.

Commercial paper cost={(interest+dealer’s commission+backup costs)/net proceed}*12=[(5,000,000*0.08*1/12)+(0.002*5,000,000*1/12)+(0.0025*5,000,000*1/12)/(5,000,000-(5,000,000*0.08*1/12)]*12=8.5%