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英数第三周周六90s1.Cagneycanfrostacupcakeevery20secondsandLaceycanfrostacupcakeevery30seconds.Workingtogether,howmanycupcakescantheyfrostin5minutes?120s2.Abugcrawlsalonganumberline,startingat-2.Itcrawlsto-6,thenturnsaroundandcrawlsto5.Howmanyunitsdoesthebugcrawlaltogether?180s3.Theproductoftwopositivenumbersis9.Thereciprocalofoneofthesenumbersis4timesthereciprocaloftheothernumber.Whatisthesumofthetwonumbers?90s4.Inabagofmarbles,3/5ofthemarblesareblueandtherestarered.Ifthenumberofredmarblesisdoubledandthenumberofbluemarblesstaysthesame,whatfractionofthemarbleswillbered?120s5.Thesumsofthreewholenumberstakeninpairsare12,17,and19.Whatisthemiddlenumber?60s6.Threerunnersstartrunningsimultaneouslyfromthesamepointona500-metercirculartrack.Theyeachrunclockwisearoundthecoursemaintainingconstantspeedsof4.4,4.8,and5.0meterspersecond.Therunnersstoponcetheyarealltogetheragainsomewhereonthecircularcourse.Howmanysecondsdotherunnersrun?140s7.Apairofsix-sideddicearelabeledsothatonediehasonlyevennumbers(twoeachof2,4,and6),andtheotherdiehasonlyoddnumbers(twoofeach1,3,and5).Thepairofdiceisrolled.Whatistheprobabilitythatthesumofthenumbersonthetopsofthetwodiceis7?140s8.Marydividesacircleinto12sectors.Thecentralanglesofthesesectors,measuredindegrees,areallintegersandtheyformanarithmeticsequence.Whatisthedegreemeasureofthesmallestpossiblesectorangle?90s9.Ayearisaleapyearifandonlyiftheyearnumberisdivisibleby400(suchas2000)orisdivisibleby4butnot100(suchas2012).The200thanniversaryofthebirthofnovelistCharlesDickenswascelebratedonFebruary7,2012,aTuesday.OnwhatdayoftheweekwasDickensborn?90s10.Chubbymakesnonstandardcheckerboardsthathavesquaresoneachside.Thecheckerboardshaveablacksquareineverycornerandalternateredandblacksquaresalongeveryrowandcolumn.Howmanyblacksquaresarethereonsuchacheckerboard?答案①25②15③15/2④4/7⑤7⑥2500⑦1/3⑧8⑨Friday⑩481