求教。

foreverdr

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.

Q Answer: D

My Q: A/D不知如何比较
对于A 如果pretax price上涨了再加上tax那麽after tax的价格就更高了 会直接导致sales降低 所以必须保证价格没有上涨。
不知错在哪里 请指教。不甚感激！

foreverdr

谢谢你!!

tengjunshan

看下面的link
http://forum.chasedream.com/GMAT_CR/thread-219737-1-13.html

tengjunshan

从别处找来，希望可以帮到你。

作者: happydw    时间: 2010-4-18 08:17

其实文章中有一个隐含的假设，就是“加税是今年导致税后价格上涨的最主要因素”。这也

就是寻找选项的指南针。
A说：加税这一年税前价格增长并不等于前一年税前价格增长。没有讨论价格上涨的原因，只是

在比较大小，纯粹无关。
B说：去年1%的销售下降就是由于加税导致的。跟今年无关，加强型无关。
C说：加税前一年如何如何，后一年如何如何。还是跟今年无关。
E说：在税后价格上涨的同时，税前价格也上涨了。这句话没能证明税后价格上涨到底是谁导致

的。

只有D排除了“加税不是导致今年税后价格上涨”的可能性，支持了隐含假设。