NO.PZ2016021706000041
问题如下：
Currently, Goodluck has $1 million in assets, financed with 100% equity. The firm's EBIT is $400,000, and its tax rate is 10%. The firm is expected to change its capital structure of 50% debt and 50% equity. Given that the cost of debt is 5%. Calculate the firm's ROE before and after the change.
选项：
ROE at 100% equity
ROE at 50% equity
36.0%
67.5%
36.0%
71.5%
60.0%
67.5%
解释：
A is correct.
Before the change:
ROE=NI/Equity=EBIT*(1-T)/Equity=400,000*(1-10%)/1,000,000=36%.
After the change:
ROE=NI/Equity=(EBIT-Int)*(1-T)/Equity=(400,000-500,000*5%)*(1-10%)/500,000=67.5%.
int 不是int expense的意思？为啥用cost of debt算？
