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题库 / OG12-CR-78
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?
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.
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.
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.
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.
Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
记有雷达为D，无雷达为D*；超速为E，未超速为E*；经常超速为R
根据题干，有：（1）n(D)/N=3%，n(D*)/N=97%，即n(D)>n(D*)；（2）n(DE)/n(E)=33%，n(D*E)/n(E)=67%，即n(DE)>n(D*E).
我们看到，条件是集合D，E之间的关系，要推出集合D，R之间的关系，一定要有集合E，R之间的关系，下面分析选项：
A.用数学语言表示：n(DE)>(E*R)，涉及集合E和R的关系，可以直接选（不放心可以继续用集合运算验证，没有问题，直接推出了结论）；
C.n(E)>n(D)，与集合E和集合R无关，不选；
D.意思是n(E)的观测值要比实际值还小，无关选项，不选；
E.讨论集合R以外的问题，无关选项，不选。
（不好意思，之前打错了符号，这是最终版，抱歉抱歉！）
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