OG-171

xiaoyuexing

NO。 171
A recent report determined that although only 3percent of drivers on Maryland highways equipped their vehicles with radar detectors, 33 percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly drivers who equip their vehicles with radar detectiors are more likely to exceed the speed limit regularly than are drivers who do not.
The conclusion drawn above depends on which of the follwoing 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 taht 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.
answer: b

我脑子实在是转不过来了，怎么推也推不出来呀！哪位高人能指点迷津。

xiaoyuexing

谢谢楼上各位！！

plmnpler

可以对B进行取非验证。

vincentwh

推理：3%equipped radar (premise1)
+33%tiketed (premise2)
--> drivers equipped radar more likely to exceed speed (conclusion)

track: ticketed 不一定就等于 exceed speed，如equipped radar后更耀眼，警察重点看防，更容易被开罚款单，但实际上并没超速。HEHE。要结论成立，必须建立如下假设：如：被ticked 就一定超速了；警察不会误开ticket；被ticked的表明更容易超速；等等。。。。

解题过程：可以对A，B，C，D，E逐个取反
A：相关：装了设备后更小可能被ticked,取反,装了设备后更大可能被ticked，解释 了为什么装了设备后更多（3%）被ticked，但起不到weaken的作用。
B: 取反,被ticked的更小可能exceed speed，则装了设备后，更多被被ticked了，但 是不一定就更大可能exceed speed，原结论不一定成立，OK，choose it.
c:原文是说百分比，C说number,无关比较。
D，E more than once, more ofen 都是无关比较。

不知道是否说清楚了，请同道兄弟点评，呵呵。

jjapollo

文章的事实是超速被开罚单的，但结论是通常的，还存在可能性是恰好偶尔超速被开了罚单但平时并不经常超速，所以必须要说明超速是一种经常的习惯，被逮到一次，其实平时一定经常这样干的。