tt gwd-4

Q4:

In the year following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent.  In contrast, in the year prior to the tax increase, sales had fallen one percent.  The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

The argument above requires which of following assumptions?

1. During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase.
2. The one percent fall in cigarette sales in the year prior to tax increase was due to a smaller tax increase.
3. The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.
4. For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.
5. As the after-tax price of a pack of cigarettes rises, the pretax price also rises.

   Answer:

我选C。

题目的意思是销售量和税后价格有很大的关系,税后价格=pretax price-tax,根据最基本的经济学供求原理,当价格上升的时候,需求量即销售量下降,那么我们来看这个税后价格的式子,如果tax上升8cent,pretax的价格同时下降8cent,则税后价格是不变的,那么供求关系也不会发生变化,亦即题目的结论就不对了,我highlight这部分就是D选项的取非,从而我们可以得出,D是正确选项

不知道我有没有解释清楚啦,假设的题型在看到not选项的时候一般先取非,放到题目中,如果结论不成立,那么这个选项就是正确的呵呵