标题: Help the 77th CR problem in OG12. [打印本页] 作者: godld 时间: 2013-4-14 15:02 标题: Help the 77th CR problem in OG12. After hours of cracking, in vain in understanding the expaination.
77. Arecent report determined thatalthoughonly3 percent ofdriversonMarylandhighwaysequipped theirvehicles
withradar detectors,33percentofall vehicles ticketed for exceeding thespeedlimit were equipped with them.
Clearly,drivers who equip theirvehicleswithradar detectors are morelikely to exceed the speed limit regularly
than aredriverswhodonot.
The conclusion drawn above depends onwhichof thefollowing assumptions?
(A) Driverswho equip their vehicleswithradardetectorsare lesslikely to be ticketed for exceeding the speed
limit than aredriverswhodonot.
(B) Driverswho are ticketed for exceeding the speedlimit are morelikely to exceed the speedlimit regularly
than aredriverswhoarenotticketed.
(C) The number of vehicles that wereticketed for exceeding the speedlimit was greaterthan the number of
vehiclesthatwereequippedwithradardetectors.
(D) Many of the vehicles that wereticketed for exceeding the speedlimit were ticketed more than once in the
time periodcoveredby thereport.
(E) Drivers on Maryland highwaysexceededthe speedlimit more often than did drivers on otherstate
highways notcoveredinthe report.
ArgumentConstruction
Situation Although only 3 percent of drivers on Maryland's highways have radar detectors in their
vehicles,33 percent ofvehiclesrecentlyticketed for drivingoverthe speed limit on
Marylandhighwayshavehad radardetectors.Drivers whohaveradardetectorsare thus
more likely toexceedthe speed limit regularly than drivers who do not.
Reasoning Whatassumptionmustbetruefortheconclusionto bedrawn?Theargumentmovesfrom a
particularexample,thatis, thepercentageofvehiclesticketed forexceedingthespeed
limit that wereequipped with radardetectors,to ageneralizationabout the regular
drivingbehaviorsof alldriverswhohaveradardetectorsin theirvehicles.Thereasoning
links theexampleto thegeneralizationwith anassumption.What can theassumption
be?Only if thedriversticketed in thisinstance areassumedtomakea regularhabit of
exceedingthespeedlimit can theconclusionbedrawnthatdriverswith radardetectors
aremorelikely to do soregularlythandriverswho are notticketed.
A While thisstatementaboutbeingticketed maybe true, theconclusionpertainsto therecurrent
exceedingof thespeedlimit, so thisstatementis notrelevant.
B Correct.Thisstatementproperlyidentifies theconclusion'snecessaryassumptionaboutticketed
drivers'beingmorelikely todriveinexcessof thespeedlimit thannonticketeddrivers.
C This statement is about the number ofvehiclesticketed, not about the regular habits ofdrivers,so
itis notassumedfortheconclusion.
D Whilethis additional information could help support theconclusion,it is not a necessary
assumptionin theconclusionbecauseit isabouttheparticularexampleof thedriversin
Maryland, not aboutdrivers'habits ingeneral.
E LearningthatMarylanddriversarenotrepresentativeofotherdriversunderminesthe conclusion
about all drivers, so it is clearlynotassumed.
ThecorrectanswerisB.作者: vaeteng 时间: 2013-4-14 15:15
大牛们的元素解题法：
A装雷达 B被罚 C超速
题目给出A到B（A装雷达易B被罚）而结论是A到C（装雷达的易超速）那么缺GapB到C（被罚的易超速）所以B啊。作者: godld 时间: 2013-5-12 18:27
assumption不是取非后削弱吗，为什么b取非不削弱，确是正确答案？？？