再问一道逻辑题。。

gmatziyu

prep logic 40题请教                                                                
                   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.
请问这题为什么选Ｂ呢？谢谢

大荣

事实，3%的司机在车上装了雷达探测器。33%的超速且被开了罚单的车装有雷达探测器。
结论，装雷达探测器的车更有可能超速比没有装的车。

注意特殊性，前提和结论讨论的对象不同。前提说的33%是讲被开了罚单的超速司机，但结论变成了说超速的司机。这就是subtle shift。有漏洞，比如可能没装雷达的车虽然经常超速，但是很少被抓住。

A.直接对结论取非。不符合not-weaken。排除。
B.弥补了推理中的断桥。
C.无关。注意这个讲的是绝对数，the number和推理中讲的percentage没有关系。排除。
D.有点迷惑，其实还是无关。只讲到被开罚单的司机，和结论中超速的司机无关。
E.无关。

gmatziyu