求助两道陈向东的《GMAT逻辑推理》里的几道假设题

Chanel800 · 发表于 2010-6-20 10:45:17

书上这个选项没有答案。是不是选A？
An acre of average farmland produces only about 400 pounds of grain amaranth, as against 2400 pounds per acre, or six times as much, for wheat. It follows that whenever the grain-amaranth price is projected to be more than six times the projected price of wheat, farmers wishing to maximize profits will grow grain amaranth rather than wheat.
The argument above is based on which of the following assumptions？
A) An acre's worth of grain amaranth is no more expensive to grow and bring to market than an acre's worth of wheat.
B) There is no crop that produces a higher yield in terms of pounds harvested per acre than wheat.
C) By choosing which crops to grow, farmers can exert a significant influence on the prices of those crops.
D) Farmers are no less motivated by the desire to maximize profits than are other occupational groups.
E) Prices of grain crops can change faster than farmers can change the acreage devoted to various grain crops.

还有这一道，这个题目和选项都读得不是很清楚。
It has been hypothesized that much of the matter in the universe is "dark", i.e., unseen. Studies have shown that galaxies in many galaxy clusters are moving faster with respect to one another than they would if visible stars constituted all their mass. The studies suggest that the galaxies are moving under the gravitational influence of unseen mass in considerable quantity.
Which of the following is an assumption underlying the passage above?
A) Measurements of the speed of moving galaxies are extremely unreliable.
B) The workings of gravitational forces are not particularly well understood.
C) The aggregate mass of visible starts in the galaxies mentioned above can be estimated with some confidence.
D) The general composition of unseen matter in the universe has been determined.
这个答案是选C。

第一次发帖，谢谢大家！

watone · 发表于 2010-6-21 12:33:47

第一题应该是 A 吧
题目中给出了售价和生产的数量，但是没有给出成本 profit = （售价-成本）* 数量所以选项应该给出成本的假设。
第二题好像是说宇宙大部分是 unseen的，然后研究表明星系（是在大部分unseen情况下的）会比都是visible（假设的情况 would if ）的情况下移动的快，最后结论是星系的移动是受这些 unseen的果然vitational的影响
至于选项不知道为什么选 C

本人非N 仅供参考

Chanel800 · 发表于 2010-6-23 07:01:33

谢LS啦！

wj37044 · 发表于 2010-7-23 22:07:13

第一题我有疑问,如果A是假设的话,对A取非结论必不成立. 但对选项A取非.即an acre's acre worth of grain amaranth is expensive to grow and bring to market than an acre worth of wheat,好象结论可能成立,可能也不成立.好象grain 成本的昂贵程度与grain 的收入的上升程度之间的大小关系不知道. 所以我觉得A好象又不是答案了. 大家来讨论一下

buda · 发表于 2010-7-23 22:29:53

In my opinion, A is right.
B: crop that produces a higher yield, this has nonbusiness with the topic
C:Farmers influence price has non business with the topic
D:Farmer's motivation has non business with the topic
E

rice change has non business with the topic

wj37044 · 发表于 2010-7-23 22:52:52

能不能这样想,如果对A 取非后,前提就有2个差异了1)收入差异2)成本差异,但结论只考虑了1个差异,所以无意义.

bennywang2usa · 发表于 2010-7-24 12:28:35

我记得关于第一题我自己总结了一个规律：凡是最后结论的落脚点在profit的，正确答案一般都是关于cost的，或者是赤裸裸地说钱的。

gmgmwll · 发表于 2010-7-29 21:55:27

如果成本高的话,人们就比一定要选择种grain 了,也是对题中说种grain的一中削弱啊

if visible stars constituted all their mass.和 The aggregate mass of visible starts 是对应的

carnice · 发表于 2010-7-29 22:24:20

第二题的C怎么解释，看不懂~~~~~

Bichenfei928 · 发表于 2010-7-30 20:47:55

哪里能找到这本陈向东的GMAT逻辑推理的解答啊？？

求助两道陈向东的《GMAT逻辑推理》里的几道假设题

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