老师麻烦解释一下这题为什么选C

问题如下：

8. In response to Cho’s question regarding an increase in unit sales above 2009 unit sales levels, it is most likely that 4G’s net income will increase at:

选项：

A.

a slower rate than Qphone’s.

B.

the same rate as Qphone’s.

C.

a faster rate than Qphone’s.

解释：

C is correct.

4G, Inc.’s degree of total leverage can be shown to equal 8, whereas Qphone Corp.’s degree of total leverage is only DOL × DFL = 1.4 × 1.15 = 1.61. Therefore, a 10 percent increase in unit sales will mean an 80 percent increase in net income for 4G, but only a 16.1 percent increase in net income for Qphone Corp. The calculation for 4G, Inc.’s DTL is

$DTL=\frac{Q(P-V)}{Q(P-V)-F-C}$

$DTL=\frac{1,000,000\times(108-72)}{1,000,000\times(108-72)-22,500,000-9,000,000}=8$