大全-2-14 大全-3-18

antoine · 发表于 2003-11-27 20:22:00

14. A recent survey of all auto accident victims in Dole County found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that, by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severely injured if they are in an auto accident.
The conclusion above is not properly drawn unless which of the following is true?
(A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents.
(B)Considerably more than 20 percent of drivers and front-seat passengers in Dole County always wear seat belts when traveling by car.
(C) More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured.
(D) More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents.
(E) Most of the auto accidents reported to police in Dole County do not involve any serious injury.
ANSWER A

18. Teresa: Manned spaceflight does not have a future, since it cannot compete economically with other means of accomplishing the objectives of spaceflight.
Edward: No mode of human transportation has a better record of reliability: two accidents in twenty-five years. Thus manned spaceflight definitely has a positive future.
Which of the following is the best logical evaluation of Edward’s argument as a response to Teresa’s argument?
(A) It cites evidence that, if true, tends to disprove the evidence cited by Teresa in drawing her conclusion.
(B) It indicates a logical gap in the support that Teresa offers for her conclusion.
(C) It raises a consideration that outweighs the argument Teresa makes.
(D) It does not meet Teresa’s point because it assumes that there is no serious impediment to transporting people into space, but this was the issue raised by Teresa.
(E) It fails to respond to Teresa’s argument because it does not address the fundamental issue of whether space activities should have priority over other claims on the national budget.
ANSWER D

14彻底对答案不理解。
18不明白的地方是选项D的最后but this was the issue raised by Teresa.是什么意思啊？
快考试了，所以很急，谢谢了！

cranberry · 发表于 2003-11-27 21:48:00

14题以前讨论过，文中说80%的伤者是没带安全带的，然而结论是带安全带会更安全，这中间存在一个gap,即带安全带的人受伤的人比例要少，而不是数量上少，因此必须要说明要么不带安全带的受访者少于80%，或者带安全带的人多于20%。

18它的意思是这正是特雷莎所提出的

antoine · 发表于 2003-11-28 09:33:00

谢谢，但是我对18还不是很明白啊！明明T说的是SPACEFLIGHT没有前途是因为ECONOMIC的原因，怎么没有IMPEDEMENT就成了T的ISSUE了呢？
还烦劳您给回答一下。
14题我后来又看过了，还是觉得不明白，特别是这个GAP，这道题其实问的是ASSUMPTION，但我不管怎么样也想不通这个GAP是怎么来的。很笨，请指教。

[此贴子已经被作者于2003-11-28 10:22:28编辑过]

miejue · 发表于 2003-11-28 23:34:00

14题根据题意严重受伤的人中80％不使用安全带结论是使用安全带降低严重受伤的风险而如果全部受调查者中（包括严重受伤和受轻伤的人）也有80％或者以上人不使用安全带那么使用安全带就对严重受伤没有影响甚至更加强可能性原结论就不成立反之要使原结论成立必须所有人中不使用安全带的比例小于80％那么使用安全带的人就要超过20％了

18题 T认为economic限制了spaceflight的future 而E反驳却是spaceflight有比较好的reliability 不就does not meet teresa’s point吗？（就像我说奶油太甜我不喜欢吃你却反驳说奶油很顺口很好吃一样你无法说服我改变看法） E的观点是因为spaceflight有比较好的reliability 所以有positive future 这里的假设就是没有比reliability更重要的评价future的因素而这个假设正是T提出的economical 因素是影响future的主要原因所以this was the issue raised by teresa 如果E想要反驳这个issue 应该直接反驳解释ecnomical不是影响future的主要原因

antoine · 发表于 2003-11-29 22:09:00

有点懂了，谢谢两位！

antoine · 发表于 2003-11-29 22:22:00

而如果全部受调查者中（包括严重受伤和受轻伤的人）也有80％或者以上人不使用安全带那么使用安全带就对严重受伤没有影响甚至更加强可能性原结论就不成立

这个又不明白了。

miejue · 发表于 2003-11-30 10:35:00

我还是给你数学证明吧假设接受调查的人中严重受伤的占X%（也就是说调查样本的严重受伤概率是X%）那么根据题意其中0.8X是没有使用安全带的（0.2X使用安全带）如果所有调查样本中不使用安全带的比例也是80％那么不使用安全带的人中严重受伤的概率也是0.8X/0.8=X% 即使用与不使用安全带概率一样而且如果样本中中超过80%不使用安全带例如90% 那么使用安全带的是10% 那么使用安全带而严重受伤的概率是0.2X/0.1＝2X，不使用安全带而严重受伤的概率是0.8X/0.9＝8X/9 甚至小于使用安全带而严重受伤的概率

现在假设样本中使用安全带的为Y% 要使原结论成立即使用安全带而严重受伤的概率小于不使用安全带而严重受伤的概率 0.2X/Y<0.8X/1-Y 解不等式可以得Y>20%

如果觉得抽象你可以自己用具体数字代入比如常用的就是假设样本容量为100人严重受伤的50人。。。。后面自己做吧

antoine · 发表于 2003-11-30 11:27:00

彻底明白了，其实画一个图可以理解得更清楚一点的。麻烦你的，打了怎么多字。

miejue · 发表于 2003-11-30 14:58:00

不客气欢迎提问

nothingwrong · 发表于 2004-10-28 16:19:00

A选项说明受轻伤的人当中带安全带的人比例比受重伤大！因此戴安全带安全

大全-2-14 大全-3-18

大全-2-14 大全-3-18

所属分类: GMAT考试

正在浏览此版块的会员 ()