请教:OC11 CR81

wangjianghua

a recent report determind that although only 3% of drivers on Maryland highways equipped their vehicles with radar detector, 33% 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 regulary than are drivers who do not.

the conclusion drawn above depends on which of the following assumption?

correct answer: (b)drivers who are ticketed for exceeding the speed limit are more likely exceed the speed limit regularly than are drivers who are not ticketed.

based on the assumption above, the conclusion, I feel, would be drawn: drivers who equip their vehicles with radar detectors are less likely to exceed the speed limit regulary than are drivers who do not.  因为被罚超车的车子里, 33% 有雷达, 67%没有雷达. 所以, 我认为得出的结论和题目的结论相反.

请问: 我的思路哪里错了?

missdandan

应该是more likely

3% equipped, while 33% of the vehicles ticheted for exceeding the

speed

按理说，3%的车有雷达，如果这些不是more likely超速的话，那么超速的

车也应该是3%有雷达

这题的关键的从一次的情况 推出 regularly 中间有逻辑的gap

wangjianghua

3% is based on all drivers on Marlyland highways. 33% is based

on the drivers who are ticketed for exceeding speed limit.

针对超车的人群, 33% 有雷达, 67%没有雷达, 根据它的前提条件:

drivers who are ticketed for exceeding the speed limit are more

likely exceed the speed limit regularly than are drivers who are

not ticketed.

得出结论是: vehicles with radar is less likly to exceed speed

limit than those without rador.

wangjianghua

哦, 我想通了.

3% 有雷达, 97% 没有雷达

33% 有雷达被罚超车, 67% 没有雷达的被罚超车,

由此可以看出, 被罚超车的比例%在有雷达的人群中比在没有雷达的人群中

要高, 所以是more likely.

前面我没有考虑3%/97%这个条件.