78. A recent report determined that although only 3 percent 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 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.(KEY) (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.作者: sdcar2010 时间: 2011-5-22 05:26
Necessary assumption. Use negation.
If you negate (B), you have: Drivers who are ticketed for exceeding the speed limit are NOT more likely to exceed the speed limit regularly than are drivers who are not ticketed. If that is the case, then for those drivers who have radar detectors and who got a speeding tickets, they are NOT more likely to exceed the speed limit regularly than are drivers who are not ticketed. This is in contrary to the concluion of the stimulus -- Drivers who equip their vehicles with radar detectors ARE more likely to exceed the speed limit regularly than are driver who do not. So if you negate (B), the stimulus falls apart. Thus, (B) is the correct answer.作者: lianlianchen 时间: 2011-5-23 02:54
Thanks a lot!作者: jun383914 时间: 2011-6-26 18:09