请教OG13中的一道逻辑题，十分感谢

grantji97

5. 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.

我看答案C才是必须的假设啊，假设有1000辆车，30辆装了雷达，但是如果被开罚单的只有10辆车，即使10辆车其中的33%装了雷达，也就是3辆，这样就不能得到题目给的结论
-装了雷达的更喜欢超速。
请各位朋友指教。

francoisyang

装雷达探测与不装的车的比例是3：97，被罚的装与不装的比例是33：67，假设所有车都上路，超速必罚，且不存在一车多次被罚的情况下，假设被罚的装雷达的车的数量是x，那么不装被罚的数量就约为2x；假设车的总数量为y，则装的车总数为3%y，不装的总数为97%y。结合一下，装的超速的比率，与不装的超速的比率相比，为(x/3%y)/(2x/97%y)=97/6，所以装了雷达探测的车更喜欢超速，而与到底装雷达探测的车的数量和被罚车的数量无关。

原文结论是装雷达探测的更喜欢超速，而之前提到的比例说的是因超速被罚而不是超速，因此必须把被罚和超速联系起来。答案我认为应该是B。

grantji97

恩，确实，我想错思路了，多谢