another Qt Q

flyingdragonamy · 发表于 2014-4-16 02:30:27

70
BY gsy930223
概率题：一共20个球，7个R色，5个B色，8个G色，一次从中那两个，问的是这两个颜色是B色和G色的概率 7/12
V2 BY asdzxcham
8红，7绿，5白球问拿出两个球为一红一白的概率答案为十九分之几不记得了

332
BY ciciwenwen
PS题：有7个red ball, 8个white ball，5个blue ball ,取2个，问是red和blue的几率。我选的应是：4/19. 我记得JJ有这道题

I think the probability should be
(red*blue)/(20*19/2)
seems only asdzxcham's answer is right

another Qt Q

所属分类: GMAT考试

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