首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Five red balls and two blue balls are placed in all empty box. One ball a time is to be selected randomly and removed 4 balls fr
Five red balls and two blue balls are placed in all empty box. One ball a time is to be selected randomly and removed 4 balls fr
admin
2021-10-21
59
问题
Five red balls and two blue balls are placed in all empty box. One ball a time is to be selected randomly and removed 4 balls from the box. What is the probability that the first two balls removed will be red and the third ball removed will be blue?
选项
A、4/21
B、4/7
D、5/7
E、2/5
答案
A
解析
第一次取出红球的概率为5/7,第二次取出红球的概率为4/6,第三次取出蓝球的概率为2/5,利用乘法原理得到所求概率为
=421,注意这道题目和直接从盒子中取出3个球(2红1蓝)的概率是有区别的,后者刚好是前者的3倍。如果用代入法来做最简单,比如随便选择一个奇数3,9-1=8,因此除以8余数为0。如果按照原理来做,则是n
2
-1=(n-1)(n+1),由于n是奇数,所以n-1和n+1是两个连续的正偶数,两个连续的正偶数的乘积必然是8的倍数,所以除以8余数为0。选择B。
转载请注明原文地址:https://kaotiyun.com/show/D3tO777K
本试题收录于:
GMAT QUANTITATIVE题库GMAT分类
0
GMAT QUANTITATIVE
GMAT
相关试题推荐
Man:Let’stakeawalk.Woman:【D8】______Man:Letmestepoutsideandsee.【D9】______Woman:SoIhavetoputonmycapandwear
Woman:Iheardyou’removingtoNewYork.Man:Yes.【D1】______Woman:Oh,that’sgreat!【D2】______Man:Me,too.Let’skeepint
Asamatteroffact,ourlifestylesarechangingand______ourbodies.
InmanywaystheInternethashadaverypositiveeffectonsociety.Ithasimprovedcommunication,simplifiedhandlingtasks,
Someofthesuggestionshavebeenadopted______othersturneddownastheyarequiteimpracticable.
Therearemanyolderpeopleintheworldandtherewillbemanymore.Alittle-knownfactisthatover60percentoftheolderp
Forthepastseveralyears,theSundaynewspapersupplementParadehasfeaturedacolumncalled"AskMarilyn."Peopleareinvite
Agoodtitleforthispassageis______.Theaveragenumberofhoursofsleepthatanadultneedsis______.
Althoughcustomprostheticbonereplacementsproducedthroughanewcomputer-aideddesignprocesswillcostmorethantwiceasm
Thereare8ballsinabox,2ofthemarered,4ofthemarewhite,2ofthemareblue.If2ballsaretobesimultaneouslyand
随机试题
《国际评估准则410——开发性不动产》对“开发性不动产”评估方法的规定中,开发性不动产的估值主要使用的两种方法是()。
催化剂的主要评价指标是()。
舌菌脾胃火毒型可选用何方治疗
促使液体回流至毛细血管内的有效胶体渗透压是()
房地产估价机构不得转让受托的城市房屋拆迁估价业务。()
甲、乙两个自然人出资设立普通合伙企业,双方订立的书面合伙协议约定:甲以10万元出资,乙以劳务出资;乙执行合伙企业事务;合伙企业利润由甲、乙分别按80%和20%的比例分配,亏损由甲、乙分别按20%和80%的比例分担。该合伙协议的约定符合《合伙企业法》的规定。
是过于集中的经济模式,而不是气候状况,造成了近年来H国糟糕的粮食收成。K国和H国耕地条件基本相同,但当H国的粮食收成造成连年下降的时候,K国的粮食收成却连年上升。以下哪项如果为真,最能削弱上述论证?
证明:n(n>3)阶非零实方阵A,若它的每个元素等于自己的代数余子式,则A是正交矩阵.
Insportthesexesareseparate.Womenandmendonotrunorswiminthesameraces.Womenarelessstrongthanmen.Thatatlea
Colorsaresometimescalledhot,cold,orneutral(中性的).Redandyellowaresaidtobehotcolorsbecausetheymakearoomwarme
最新回复
(
0
)