OG-171

CasualWalk

我察了一下好像这题没讨论过(免得1stzhang又来骂我)

171. A recent report determined that although only three percent of drivers on Maryland
highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles
ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip
their vehicles with radar detectors are more likely to exceed the speed limit regularly than
are drivers who do not.
The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for
exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the
speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater
than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed
more than once in the time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on
other state highways not covered in the report.

答案B。我的理解是B说明sample代表全部，不知对不对？可是，我觉得A也有道理 -
vechiles with radar detectors不容易被抓住，不是也证明结论吗？

我感觉这题我没有抓到筋，下次可能还错。请指教解题思路，谢谢！

patrick

这个题目我的思路是，题目有2个PREMISE：1。3%的车有RADAR，2，33%的被抓的车有RADAR，CONCLUSION：有RADAR的车容易超速，比较2个PREMISE可以看出题目应该基于的假设是被抓的人就是容易超速的人。
A，并没有把超速和被抓联系起来，太只是解释PREMISE2的一种可能的原应。
不对的地方请指教！

mindfree

同意patrick的意见, 我稍微总结一下

此题中有一个gap,是概念的跳跃,原文通过说明装radar detector的在所有车的比例和被ticket的车的比例得出装RD的人经常超速. 这里的两个概念是ticketed和regularly exceed speed limit.由两个数据我们可以直接得到(无需任何隐含条件)的是:装RD的车更多的被ticket.而结论直接将ticket和regularly  exceed speed limit联系在一起,这就是概念上的跳跃,需要一个assumption将两个概念联系在一起,即B

顺便提一句, 此题以前讨论过...

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呵呵,开玩笑的.

CasualWalk

多谢二位！

liu_9000

刚看了几个关于这题的几个帖子,发现一个很有意思的问题, 大家试着翻译一下A选项:

(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for
exceeding the speed limit than are drivers who do not.

这选项我上来就当加强处理了,看了几张帖说是削弱. 原来这个选项可以有两种理解(不知道ETS是不是有意这么设计的)

翻译: 装了雷达探测器的司机们比不装的更少可能因为超速吃罚单.

理解1: 大家都超速, 但我装了探测器, 被抓的机会小.(简化为: 少吃罚单, 没少超速)

理解2: 虽然我装了雷达探测器, 但我是好市民, 吃罚单都是因为闯红灯什么的, 因为超速而吃罚单少.(简化为: 少超速, 当然少吃超速罚单, )

虽然两种理解对答案都没有影响, 但是对削弱还是加强可是至关重要. 大家发表下意见呀

Andrea625

你想多了。题中没有讨论装Radar是否能超速却少被抓（事实是装可能更危险，因为现在禁止装。这说的更远了），也没有讨论超速以外原因导致的罚单。建议你还是忘了这些吧。

看来达不到mindfree的水平就只好通过取非做题了。看mindfree说的象搭积木一样，直观的很啊。

[此贴子已经被作者于2004-6-15 15:09:18编辑过]

ercizhang

文中描述的是:the percent (of drivers who equip their vehicles with radar detectors exceed the speed limit regularly) is greater than that of drivers who do not. 强调数量 即:isolated occasions when drivers exceed the speed limit

而结论drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.强调频率:concerns regularly exceeding the speed limit

这两个概念中间需要桥梁,即rivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed

ercizhang

装RD的车更多的被ticket,不是更经常的被ticket,概念不同

QQgt

用取非削弱， A就更像答案了。

我爱欧洲

这题用mindfree的gap法基本就可以解决了。我再引用OG的补充一点：结论的重点是regularly经常性超速，而题干的数据是孤立的数据。这题就是典型的由偶然孤立的数据---》有代表性的经常性数据。之间的GAP就是，偶然的数据有代表性。