GMAT两大数学题求解答
1.Eachparticipantinacertainstudywasassignedasequenceof3differentlettersfromtheset{A,B,C,D,E,F,G,H}.Ifnosequencewasassignedtomorethanoneparticipantandif36ofthepossiblesequenceswerenotassigned,whatwasthenumberofparticipantsinthestudy?(Note,forexample,thatthesequenceA,B,CisdifferentfromthesequenceC,B,A.)
A.20
B.92
C.300
D.372
E.476
StationsXandYareconnectedbytwoseparate,straight,parallelraillinesthatare250mileslong.TrainPandtrainQsimultaneouslyleftStationXandStationY,respectively,andeachtraintraveledtotheother’spointofdeparture.Thetwotrainspassedeachotheraftertravelingfor2hours.Whenthetwotrainspassed,whichtrainwasnearertoitsdestination?
(1)Atthetimewhenthetwotrainspassed,trainPhadaveragedaspeedof70milesperhour.
(2)TrainQaveragedaspeedof55milesperhourfortheentiretrip.
A.Statement(1)ALONEissufficient,butstatement(2)aloneisnotsufficient.
B.Statement(2)ALONEissufficient,butstatement(1)aloneisnotsufficient.
C.BOTHstatementsTOGETHERaresufficient,butNEITHERstatementALONEissufficient.
D.EACHstatementALONEissufficient.
E.Statements(1)and(2)TOGETHERareNOTsufficient.
第一题答案为C,第二题答案为A.