求解一道令人头秃的逻辑题目

lwtSerena666

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.

问assumption？

• 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.
• The one percent fall in cigarette sales in the year prior to tax increases was due to a smaller tax increase.
• The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.
• 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.
• As the after-tax price of a pack of cigarettes rises, the pretax price also rises.
  

在D和E之间犹豫不定，跪求大神解答！！！！！！！！

ShayneYang

公式：pretax price+tax=after-tax price，现在tax涨了8分，要说明的是税后价和销售量的关系，即税后价上涨导致销售量下降，那就要要求after-tax price较之去年要高，因此pretax price较之去年不能下降超过8分，因此D正确。

taurus_gzy

结论是：税后价格和销量有关；意思税后价格增加，销量就下降了；
假设之前价格pre-price是100 cents /tax 2 cents 税后价格是102 cents
对于d，税前价格没有比之前的低于 8 cents或者更多
取上限 税前价格低了7 cents pre-price 93 cents tax 2+8cents 税后价格是103cents 比之前的102 cents 高
所以影响了sale

取非是 低于8cents或者更多 那税后价格就是小于等于102cents
税后价格反而低了，所以不是税后价格的变化使sale减少

taurus_gzy

至于E的话
税前价格也增加了，所以不能说明结论：The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.