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GMAT数学1
GMAT数学
第一部分数学基础知识
一、代数Algebra
例1比较大小:
.
Thenumberofdistinctpositivefactorsofn14比较大小
例2:
252因子的个数是多少?
例3比较大小:
Aprinternumberedconsecutivelythepagesofabook,beginningwith1onthefirstpage.Innumberingthepage,heprintedatotalof204digits.
Thenumberofpagesinthebook105
例4比较大小:
Inacertaintwo-digitnumber,
theunits'digitistwicethetens'digit.5
Thetens'digit
例5比较大小:
二、描述统计descriptivestatistics
例6比较大小:
某长方形的周长为40,该长方形的最大面积100
例7比较大小:
空间5个点能够构成的直线数目10
例8:
求3,13,17的标准方差。
三、排列组合combination、概率probability
1.排列组合排列计算公式:
,组合计算公式:
。
2.概率
例9:
假如世界杯比赛共有32支球队,分成8个组,每组4个队,每组前两名出线,然后成对进行淘汰赛,直至决赛决出冠军,并且淘汰队不参加比赛,从中间任选出一场比赛观看是半决赛的机会有多大?
例10:
有4对男女,每对中有1男1女,从每对中选出1人,选出2男2女的概率是多少?
例11:
有3个打字员为4家公司服务,如果4家公司各有1份文件要录入,他们只能找到这3个打字员录入,且各公司对打字员的要求是随机的。
问每个打字员都收到文件的概率是多少?
例12:
两个骰子,六面的值分别为1,2,3,4,5,6,投掷这两个骰子,问其中一个骰子的值比另一个的值大2的概率为多大?
四、几何(Geometry)
例13比较大小:
RisapointintherectangularcoordinatesystemandOR=5.
Thex-coordinateofpointR54.9
例14比较大小:
(RS)2+(ST)2(RT)2
例15:
Accordingtothegraphabove,whenx=3,yismostnearly:
(A)-1(B)-1/2(C)0(D)1/2(E)1
五、文字题(WordProblem)
1.利息问题(interest)
单利simpleinterest复利compoundinterest
例16:
If$8000isinvestedat6percentsimpleannualinterest,howmuchinterestisearnedafter3months?
例17:
If$10,000isinvestedat10percentsimpleannualinterest,compoundsemiannually,whatisthebalanceafter1year?
2.折扣问题(discount)
例18:
Thepriceofanitemisdiscountedby20percentandthenthisreducedpriceisdiscountedbyanadditional30percent.Thesetwodiscountsareequaltoanoveralldiscountofwhatpercent?
3.英美常识问题
GRE难题解析
例1:
Onacertainnumberline,if-7isadistanceof4fromnand7isadistanceof18fromn,thenn=?
(A)25(B)11(C)-3(D)11(E)-11
例2:
Thediagramrepresentsarectangulargarden.Theshadedregionsareplantedinflowers,andtheunshadedregionisawalk2feetwide.Allanglesarerightangles.
Thesumoftheareasofthe2,800squarefeet
shadedregions
例3:
Themapshowstheonlyroadsthatconnectthefourtownsandshowsthedistancealongeachroad.
TheroaddistancebetweenAustenandSeburg
TheroaddistancebetweenCoaltownandWoodland
例4:
Howmanypositiveintegerslessthan20areequaltothesumofapositivemultipleof3andapositivemultipleof4?
(A)Two(B)Five(C)Seven(D)Ten(E)Nineteen
例5:
Whichofthefollowingsymbolsshouldbesubstitutedfor
tomakebothofthestatementstrueforallintegersnsuchthat-2(A)≤(B)<(C)=(D)>(E)≥
4-n
6
4-n
5
例6:
Inasoccerleague,Iftherewere10teamsandeachteamplayedeachoftheotherteams16times,howmanygamesdideachteamplay?
(A)144(B)140(C)134(D)125(E)106
例7:
(NOTE:
DRAWNTOSCALE)
POPULATIONOFTHEU.S.AGE55ANDOVER
1984ANDPROJECTIONSFOR1995
INCOMEDISTRIBUTIONFORPOPULATION
OFTHEU.S.AGE55ANDOVER,1984
In1984medianincomeforapersoninthe55~64agecategorywasinwhichofthefollowingintervals?
(A)lessthan$10,000(B)$10,000~$19,999(C)$20,000~$24,999(D)$25,000~$34,999(E)$35,000~$49,999
例8:
Asampleofemployeesweretastedondata-entryskillsforonehour,andthenumberoferrors(x)theymadeandthepercentofemployees(p)makingxerrorswererecordedasfollows.
Numberoferrorx
0
1
2
3
4
5
6ormore
PercentofemployeesP
2%
5%
10%
24%
14%
20%
22%
whatwasthemediannumberoferrorsinthesample?
(A)3(B)3.5(C)4(D)4.5
(E)Itcannotbedeterminedfromtheinformationgiven.
例9:
d=7.56872andDisthedecimalexpressionfordroundedtothenearestthousandth.
ThenumberofdecimalplacewheredandDdiffer
4
例10:
Inacertaincountry,apersonisbornevery3secondsandapersondiesevery10seconds.Therefore,thebirthanddeathratesaccountforapopulationgrowthrateofonepersonevery
例11:
Ofthepositiveintegersthataremultiplesof30andarelessthanorequalto360,whatfractionaremultiplesof12?
(A)1/6(B)1/5(C)1/3(D)2/5(E)1/2
8inches
例12:
ThefigureshowsalargesquareformedbyfittingthreeL-shapedtilesandonesmallsquaretiletogether.Ifarectangularfloor10feetby12feetistobetiledinlargesquaresofthisdesign,howmanyL-shapedtileswillbeneeded?
(A)810(B)405(C)270(D)135(E)45
8inches
例13:
Thedailyrateforahotelroomthatsleeps4peopleis$39foronepersonandxdollarsforeachadditionalperson.If3peopletaketheroomforonedayandeachpays$21fortheroom,whatisthevalueofx?
(A)6(B)8(C)12(D)13(E)24
例14:
Apositiveintegerwithexactlytwodifferentdivisorsgreaterthan1mustbe
(A)aprime(B)aneveninteger(C)amultipleof3
(D)thesquareofaprime(E)thesquareofanoddinteger
例15:
x>z,y>zx+yz
例16:
x>yandxy≠0(x+y)/x(x+y)/y
例17:
2AF=AB=BD=DE=AE
ThesumoftheareaoftriangularregionABFandareaoftriangularregionCDE
TheareaofrectangularregionBCEF
例18:
Eachofthefollowingnumbershastwodigitsblottedout.Whichofthenumberscouldbethenumberofhoursinxdays,wherexisaninteger?
(A)25
06(B)50
26(C)56
02(D)62
50(E)65
20
例19:
Thereare1200representstoapoll,eachfavoringtheirpreferenceforcandidatesA,B,andC.54%favoredA,48%favoredB,and42%favoredC,andthereis30%favoredbothAandB.What’sthelargestpossiblenumberofrepresentsfavoringc,butnotC&B,norC&A?
(A)25%(B)30%(C)28%(D)38%(E)40%
例20:
Outof100ladiesattendingthechurchfete,85hadawhitehandbag;75hadblackshoes;60carriedanumbrella;90worearing,Howmanyladiesmusthavehadallfouritems?
(A)15(B)35(C)5(D)10(E)25
例21:
Inaninsurancecompany,eachpolicyhasapaperrecordandanelectricrecord.Forthosepolicieshavingincorrectpaperrecord,60%alsohavingincorrectelectricrecord;Forthosepolicieshavingincorrectelectricrecord,75%alsohavingincorrectpaperrecord.3%ofallpolicieshavebothincorrectpaperandincorrectelectricrecord.Ifwerandomlypickoutonepolicy,what’stheprobabilitythattheonehavingbothcorrectpaperandcorrectelectricrecord?
(A)0.80(B)0.94(C)0.75(D)0.88(E)0.92
ak
100
200
300
400
500
pk
0.10
0.25
0.20
0.25
0.20
例22:
Ifinanexperimenttheprobabilitiesofobtainingthevaluesa1,a2,a3,a4,a5arep1,p2,p3,p4,p5,respectively,thentheexpectedvalueisdefinedasa1p1+a2p2+a3p3+a4p4+a5p5.Forthevaluesandtheircorrespondingprobabilitiesinthetableabove,whatistheexpectedvalue?
(A)350(B)320(C)300(D)270(E)250
例23:
Thestandarddeviationofthesamplemeasurements0,2,4,6,and8
Thestandarddeviationofthesamplemeasurements1,3,5,7,and9
例24:
Whatisthetotalnumberofdifferent5-digitnumbersthatcontainallofthedigits2,3,4,7and9andinwhichnoneoftheevendigitsoccurnexttoeachother?
(A)72(B)100(C)120(D)60(E)48
例25:
Wateristobepouredatarateof2.5gallonsperminuteintoa500-gallontankthatinitiallycontains50gallonsofwater.
Thepercentofthetank'scapacitythatwillbe
filled1hourafterwaterbeginstobepouredin
60percent
例26:
Inthefigure,ifx,y,andzareintegerssuchthatx(A)59and91(B)69and135(C)91and178(D)120and135(E)120and178
例27:
Thefigureshowsthedimensionsofrectangularboxthatistobecompletelywrappedwithpaper.Ifasinglesheetofpaperistobeusedwithoutpatching,thenthedimensionsofthepapercouldbe
(A)17inby25in(B)21inby24in(C)24inby12in
(D)24inby14in(E)26inby14in
例28:
Inthetable,whatistheleastnumberoftableentriesthatareneededtoshowthemileagebetweeneachcityandeachoftheotherfivecities?
(A)15(B)21(C)25(D)30(E)36
例29:
Astorecurrentlychargesthesamepriceforeachtowelthatitsells.Ifthecurrentpriceofeachtowelwastobeincreasedby$1,10fewerofthetowelscouldbeboughtfor$120,excludingsalestax.Whatisthecurrentpriceofeachtowel?
(A)$1(B)$2(C)$3(D)$4(E)$12
GRE数学常用符号及术语
一.数学中常用符号
+:
plus X:
multiply
-:
subtract ÷:
divide
V~:
square root |...|:
absolute value
=:
is equal to =/=:
is not equal to
>:
is greater than <:
is less than
//:
is parallel to _|_:
is perpendicular to
>=:
is greater than or equal to (或 no less than)
<=:
is less than or equal to (或no more than)
二.表达相应数目的前缀
1:
uni-,mono- 2:
bi-,du-,di- 3:
tri-,ter-, 4:
tetra-,quad-, 5:
penta-,quint,
6:
hex-,sex-, 7:
sept-,hapta-, 8:
oct, 9:
enn-, 10:
dec-,deka-,
三.数学中常用单词术语
abscissa
横坐标
absolutevalue
绝对值
acuteangle
锐角
adjacentangle
邻角
addition
加
algebra
代数
altitude
高
anglebisector
角平分线
arc
弧
area
面积
arithmeticmean
算术平均值(总和除以总数)
arithmeticprogression
等差数列(等差级数)
arm
直角三角形的股
at
总计(乘法)
average
平均值
base
底
becontainedin
位于...上
bisect
平分
center
圆心
chord
弦
circle
圆形
circumference
圆周长
circumscribe
外切,外接
clockwise
顺时针方向
closestapproximation
最相近似的
combination
组合
commondivisor
公约数,公因子
commonfactor
公因子
complementaryangles
余角(二角和为90度)
Compositenumber
合数(可被除1及本身以外其它的数整除)
concentriccircle
同心圆
cone
圆锥(体积=1/3*∏*r*r*h)
congruent
全等的
consecutiveinteger
连续的整数
coordinate
坐标的
cost
成本
counterclockwise
逆时针方向
cube
1.立方数
2.立方体(体积=a*a*a 表面积=6*a*a)
cylinder
圆柱体
decagon
十边形
decimal
小数
decimalpoint
小数点
decreased
减少
decreaseto
减少到
decreaseby
减少了
degree
角度
define
1.定义2.化简
denominator
分母
de