请教OG12 CR-78

莉小莉

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.

关于B和D的讨论我看过，也都明白。我不明白的是OG对于A的解释，

我觉得A错是因为

题干说装了雷达设备更容易被开罚单，但是A却说装了雷达被开罚单的可能性就小了。
我认为这与题干相反，所以错。

但是OG的解释是：
While this statement about being ticketed <may be true>, the conclusion pertains to the recurrent
exceeding of the speed limit, so this statement is not relevant.

为什么会may be true啊？不是很明显against 题目吗？

谢谢！

howfay

题目只是说了两个数据，并没有做出“装了雷达系统的人更容易被开罚单”这样的结论。
可以举一个这样的例子，如果一辆没有装载雷达系统的汽车每次超速都会被记录，可是一辆装了雷达系统的汽车每三次超速才会被记录一次。
可能是因为装了雷达系统使得汽车超速不容易被抓住，所以才使得装了雷达系统的汽车超速的频率高了。比如一辆没装系统的汽车100次里面超速10次被抓了，一辆装了系统的汽车100次超速60次被抓了20次
这也部分论证了B选项

莉小莉

题目只是说了两个数据，并没有做出“装了雷达系统的人更容易被开罚单”这样的结论。
可以举一个这样的例子，如果一辆没有装载雷达系统的汽车每次超速都会被记录，可是一辆装了雷达系统的汽车每三次超速才会被记录一次。
可能是因为装了雷达系统使得汽车超速不容易被抓住，所以才使得装了雷达系统的汽车超速的频率高了。比如一辆没装系统的汽车100次里面超速10次被抓了，一辆装了系统的汽车100次超速60次被抓了20次
这也部分论证了B选项

-- by 会员 howfay (2011/7/27 14:54:51)

谢谢你，
可是呢，不管装了雷达之后超速的实际频率如何，被开罚单的量确实是增多了。因为如果数量没有增多的话，那被开罚单的总量里也应该只有3%是安了雷达的才对。比例提高了说明安装雷达之后确实被开罚单的几率提高了，不管这个是由于它平常超速频率高了都被抓住了，还是平常超速频率没有变，但是装了之后就是邪门了，更容易被捉住。


另外，我觉得http://forum.chasedream.com/GMAT_CR/thread-276498-3-1.html 对于理解正确选项很有帮助。
我对于A的解释还是有一些困惑。


再次感谢。

秋叶蠖

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.

我是这样理解的，前提说：30%exceeding=radar
   
                           结论说：radar=more likely to exceed

于是，在二者非公有信息间建立逻辑链，就得到了30%exceeding=more likely to exceed，就是答案B所说的

(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.

莉小莉

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.

我是这样理解的，前提说：30%exceeding=radar
   
                           结论说：radar=more likely to exceed

于是，在二者非公有信息间建立逻辑链，就得到了30%exceeding=more likely to exceed，就是答案B所说的

(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.

-- by 会员 秋叶蠖 (2011/7/28 18:49:56)

谢谢。
可是……我明白B耶……我不明白的是A的OG解释……

mizleave

正如一楼所说：题目只是说了两个数据，并没有做出“装了雷达系统的人更容易被开罚单”这样的结论。
题目中说被罚超速的人中有33%安装了雷达，而没安装的有67% ，所以，如A所说，装了雷达的人反而不太容易被罚超速，这种可能性就印证了A的解释may be true，而不是一定true。