Datainferences1.Arandomsampleof35four-doorpassengervehicleshadameangasmileage,inmilespergallon(mpg),of25.9mpg.Theestimatehadamarginoferrorof2.6mpgata98%confidencelevel.Ofthefollowing,whichismostplausiblevalueforthetruemeanofthemileageoffour-doorpassengervehiclesingeneral?A.24mpgB.29mpgC.32mpgD.35mpgCorrectanswer:ADifficultylevel:22.Basedonrandomsamplesofriverheights,oceanographersestimatethat4,800cubickilometers(km3)offreshwaterisdischargedintotheArcticOceanannually.Theestimatehasamarginoferrorof240km3atthe90%confidencelevel.WhichofthefollowingisthemostreasonableclaimaboutthevolumeoffreshwaterdischargedannuallyintotheArcticOcean?A.Itisbetween4,800and5,040km3.B.Itisbetween4,560and5,040km3.C.Itisbetween240and4800km3.D.Itisbetween240and4320km3.Correctanswer:BDifficultylevel:23.Asurveyof9,000randomlyselecteddentistspracticingintheUnitedStates(US)foundthat3,600ofthemusedtextmessagingtoremindclientsofupcomingappointments.Iftherewere147,000practicingdentistsintheUS,approximatelyhowmanyofthemusedtextmessagingforthatpurpose?A.12,600dentistsB.58,800dentistsC.159,600dentistsD.367,500dentistsCorrectanswer:BDifficultylevel:24.Arandomsampleofinternationalflightsin2013showedthat79%oftheflightsarrivedwithin15minutesoftheirscheduledarrivaltime,andthisestimatehadamarginoferrorof3%ata95%confidencelevel.Whichofthefollowingconclusionsisbest?A.Exactly79%arrivedwithin15minutesoftheirscheduledtimes.B.Exactly76%arrivedwithin15minutesoftheirscheduledtimes.C.Between76%and82%arrivedwithin15minutesoftheirscheduledtimes.D.Between92%and98%arrivedwithin15minutesoftheirscheduledtimes.Correctanswer:CDifficultylevel:25.Inapollof1,578randomlyselectedAmericanadults,44.8%oftherespondentssaidthatairlinesshouldallowin-flightcallsonairplanes.Theresultshadamarginoferrorof2.5%ata90%confidencelevel.WhichofthefollowingismostlikelytobeequaltothepercentageofallAmericanadultswhowouldsaythatairlinesshouldallowin-flightcalls?A.40%B.43%C.48%D.90%Correctanswer:BDifficultylevel:26.Inastudyof40randomlyselectedcaptiv...
