分享五道高频GRE数学试题答案及解析

GRE数学部分对于考生来说是难度相对较低的，考生也期望着能够在这个部分表现出色拿到高分满分以提升总成绩。本文将GRE数学各大高频考点题型的具体讲解和解题思路剖析，确保考生不在简单数学部分意外失分，顺利拿到高分满分！

题目1.Aboxcontains100balls,numberedfrom1to100.Ifthreeballsareselectedatrandomandwithreplacementfromthebox,whatistheprobabilitythatthesumofthethreenumbersontheballsselectedfromtheboxwillbeodd?

A.1/4

B.3/8

C.1/2

D.5/8

E.3/4

答案：C

解析：本题因为奇数和偶数个数相同，和也只有两种方式，所以三个数的和为奇数的可能性为1/2。也可以考虑从这100个数中任取三个数的奇偶，可能性为：奇奇奇，奇偶偶，奇奇偶和偶偶偶，其中奇奇奇和奇偶偶两种情况的和为奇数，所以也得到可能性为1/2

2.Thereare1200respondentstoapoll,eachfavoringtheirpreferenceforcandidatesA,B,andC.54%favoredA,48%favoredB,and42%favoredC,andthereis30%favoredbothAandB.What’sthelargestpossiblenumberofrespondentsfavoringC,butnotC&B,norC&A?

A.25%

B.30%

C.28%

D.38%

E.40%

解析：A和B的并集为：54%48%-30%=72%，所C为28%

3.Inaninsurancecompany,eachpolicyhasapaperrecordandanelectricrecord.Forthosepolicieshavingincorrectpaperrecord,60%alsohavingincorrectelectricrecord;Forpolicieshavingincorrectelectricrecord,75%alsohavingincorrectpaperrecord.3%ofallpolicieshavebothincorrectpaperandincorrectelectricrecords.Ifwerandomlypickoutonepolicy,what’stheprobabilitythattheonehavingbothcorrectpaperandcorrectelectricrecords?A.0.80

B.0.94

C.0.75

D.0.88

E.0.92

答案：B

解析：设总数为x，设incorrectpaperrecord有y,incorrectelectricrecord有z，则：

x·y·60%=3%·xy=5%

x·z·75%=3%·xz=4%

则，两者至少有一个错误的百分比为5%4%-3%=6%，所正确答案为94%

4.IfBobcandoajobin20daysandJanecandothejobin30days,theyworktogethertodothisjobandinthisperiod,Bobstopworkfor2.5daysandJanestopworkforxdays,andthejobbefinishedfor14days,whatisx?

A.1.6

B.3.2

C.1.5

D.1.25

E.1.15

答案：D

解析：

1/20(14-2.5)1/30(14-x)=1，得出x=1.25

5.TheprobabilityofAis60%andtheprobabilityofBis50%,whatisthemostpossibleprobabilitythatneitherAnorBwouldhappen?B.0.40

D.0.55

E.0.68

解析：划出图表来可以一目了然：A，B均不发生的大概率为40%，小概率为0.因此选B