问题如下图：
选项：
A. 
B. 
C. 
解释：
原来的GPM=47/152.38=30.84%
后来的GPM=152.38-（105.38*0.04*1.2+105.38）/152.38=27.52%
30.84%-27.52%=3.32%为啥选A???
不能先算GPM再减，要分别把COGS算出来减了之后再除以SALES是为什么？其他类似的计算也是这样进行的吗？先算GPM和后算GPM有啥区别？
NO.PZ201512300100000705 我不懂变化量和成本之间的关系 我这章节涉及变化率的没一个算对，真的想哭
NO.PZ201512300100000705 The sensitivity analysis consists of increase of 20% in the priof input thconstitutes 4% of cost of sales. Change in grossprofit margin because of thincrease is calculatethe change in cost of sales because of priincrease visales: = (Cost of sales × 0.04 × 0.2)/Sales = (105.38 × 0.04 × 0.2)/152.38 = 0.0055 为什么不是*1.2*（1-4%）
NO.PZ201512300100000705 老师好 为什么 这里分母不是乘以 1.2 而是乘以0.2 “(Cost of sales × 0.04 × 0.2)/Sales” 谢谢 ， 讲义里 有总结过 increase xx from xx , 是 + x%； increase x%是指 G *（1+x%）。 题中”increase “ 该怎么理解 是和incease X% 的意思不同的，是吗？
NO.PZ201512300100000705 老师好，我把计算步骤列出来了，带一撇的是变化后的意思，谢谢老师。
NO.PZ201512300100000705 0.80 percentage points. 3.32 percentage points. A is correct. The sensitivity analysis consists of increase of 20% in the priof input thconstitutes 4% of cost of sales. Change in grossprofit margin because of thincrease is calculatethe change in cost of sales because of priincrease visales: = (Cost of sales × 0.04 × 0.2)/Sales = (105.38 × 0.04 × 0.2)/152.38 = 0.0055Profit margin的计算不是应该为SALES-COGS/SALES,而答案用COGS/SALES?
