2018年AMC8考题和答案解析

-.z.2021AMC8考题及答案Problem1Whichofthefollowingvaluesislargest"Problem2Alicia,Brenda,andColbywerethecandidatesinarecentelectionforstudentpresident.Thepiechartbelowshowshowthevotesweredistributedamongthethreecandidates.IfBrendareceived36votes,thenhowmanyvoteswerecastalltogether"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_2Problem3Whatisthevalueofthee*pression"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_3Problem4When0.000315ismultipliedby7,928,564theproductisclosesttowhichofthefollowing"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_4Problem5Whatisthevalueofthee*pression"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_5Problem6Ifthedegreemeasuresoftheanglesofatriangleareintheratio,whatisthedegreemeasureofthelargestangleofthetriangle"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_6Problem7Letbea6-digitpositiveinteger,suchas247247,whosefirstthreedigitsarethesameasitslastthreedigitstakeninthesameorder.Whichofthefollowingnumbersmustalsobeafactorof"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_7Problem8MalcolmwantstovisitIsabellaafterschooltodayandknowsthestreetwhereshelivesbutdoesn'tknowherhousenumber.Shetellshim,"Myhousenumberhastwodigits,ande*actlythreeofthefollowingfourstatementsaboutitaretrue."(1)Itisprime.(2)Itiseven.(3)Itisdivisibleby7.(4)Oneofitsdigitsis9.ThisinformationallowsMalcolmtodetermineIsabella'shousenumber.Whatisitsunitsdigit"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_8Problem9AllofMarcy'smarblesareblue,red,green,oryellow.Onethirdofhermarblesareblue,onefourthofthemarered,andsi*ofthemaregreen.WhatisthesmallestnumberofyellowmarblesthatMarcycouldhave"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_9Problem10Abo*containsfivecards,numbered1,2,3,4,and5.Threecardsareselectedrandomlywithoutreplacementfromthebo*.Whatistheprobabilitythat4isthelargestvalueselected"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_10Problem11Asquare-shapedflooriscoveredwithcongruentsquaretiles.Ifthetotalnumberoftilesthatlieonthetwodiagonalsis37,howmanytilescoverthefloor"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_11Problem12Thesmallestpositiveintegergreaterthan1thatleavesaremainderof1whendividedby4,5,and6liesbetweenwhichofthefollowingpairsofnumbers"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_12Problem13Peter,Emma,andKylerplayedchesswitheachother.Peterwon4gamesandlost2games.Emmawon3gamesandlost3games.IfKylerlost3games,howmanygamesdidhewin"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_13Problem14ChloeandZoearebothstudentsinMs.Demeanor'smathclass.Lastnighttheyeachsolvedhalfoftheproblemsintheirhomeworkassignmentaloneandthensolvedtheotherhalftogether.Chloehadcorrectanswerstoonlyoftheproblemsshesolvedalone,butoverallofheranswerswerecorrect.Zoehadcorrectanswerstooftheproblemsshesolvedalone.WhatwasZoe'soverallpercentageofcorrectanswers"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_14Problem15Inthearrangementoflettersandnumeralsbelow,byhowmanydifferentpathscanonespellAMC8"BeginningattheAinthemiddle,apathallowsonlymovesfromonelettertoanadjacent(above,below,left,orright,butnotdiagonal)letter.Onee*ampleofsuchapathistracedinthepicture.artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_15Problem16Inthefigurebelow,choosepointonsothatandhaveequalperimeters.Whatistheareaof"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_16Problem17Startingwithsomegoldcoinsandsomeemptytreasurechests,Itriedtoput9goldcoinsineachtreasurechest,butthatleft2treasurechestsempty.SoinsteadIput6goldcoinsineachtreasurechest,butthenIhad3goldcoinsleftover.HowmanygoldcoinsdidIhave"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_17Problem18Inthenon-conve*quadrilateralshownbelow,isarightangle,,,,and.Whatistheareaofquadrilateral"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_18Problem19Foranypositiveinteger,thenotationdenotestheproductoftheintegersthrough.Whatisthelargestintegerforwhichisafactorofthesum"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_19Problem20Anintegerbetweenand,inclusive,ischosenatrandom.Whatistheprobabilitythatitisanoddintegerwhosedigitsarealldistinct"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_20Problem21Suppose,,andarenonzerorealnumbers,and.Whatarethepossiblevalue(s)for"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_21Problem22Intherighttriangle,,,andangleisarightangle.Asemicircleisinscribedinthetriangleasshown.Whatistheradiusofthesemicircle"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_22Problem23Eachdayforfourdays,Lindatraveledforonehourataspeedthatresultedinhertravelingonemileinanintegernumberofminutes.Eachdayafterthefirst,herspeeddecreasedsothatthenumberofminutestotravelonemileincreasedby5minutesovertheprecedingday.Eachofthefourdays,herdistancetraveledwasalsoanintegernumberofmiles.Whatwasthetotalnumberofmilesforthefourtrips"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_23Problem24Mrs.Sandershasthreegrandchildren,whocallherregularly.Onecallshereverythreedays,onecallshereveryfourdays,andonecallshereveryfivedays.AllthreecalledheronDecember31,2021.Onhowmanydaysduringthene*tyeardidshenotreceiveaphonecallfromanyofhergrandchildren"artofproblemsolving./wiki/inde*.php"title=2021_AMC_8_Problems/Problem_24Problem25Inthefigureshown,andarelinesegmentseachoflength2,and.Arcsandareeachone-si*thofacirclewithradius2.Whatistheareaoftheregionshown"2021AMC8AnswerKeyAECDBDADDCCDBCDDCBDBADCDB