OG-171

bnbf

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！

topway5

同意apple1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

apple1

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！