9. 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?
A. 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.
B. The one percent fall in cigarette sales in the year prior to tax increase was due to a smaller tax increase.
C. The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.
D. 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.
E. As the after-tax price of a pack of cigarettes rises, the pretax price also rises.
答案为D
原文推理：税收增加8CENTS，销售量就下降。所以销售量和税后价格关系密切（即加税使税后价格升高导致销售量下降）
D说税前价格没有比去年（加税那年）便宜8CENTS或更多。将D取非，则现在的税后价格比原来还便宜，虽然税收长了8CENTS，这说明不是税后价格影响销售量，两者没有STRONGLY RELATED。结论不成立。故为假设
lawyer:
我对这种数字的假设题很恐惧 一见数字就怕
你说这个8%对题目有没有影响 我感觉如果改为10%或者20% 只要答案也跟着改 实际没有什么影响
是不是这种题 说到底就是排除他因 无论数字如何
谢谢
答案为D
D说税前价格没有比去年（加税那年）便宜8CENTS或更多。将D取非，则现在的税后价格比原来还便宜，虽然税收长了8CENTS，这说明不是税后价格影响销售量，两者没有STRONGLY RELATED。结论不成立。故为假设
D取非如何会变成
现在的税后价格比原来还便宜
我脑子转不过弯来了
1。是8CENTS，即8分，不是8%
2。将D取非为：税前价格比去年（加税那年）低8CENTS以上。则加上8CENTS税后，税后价格比去年还是低。这样价格影响销售就不成立了。
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