数学问题概率求解释Reworkproblem28fromse-查字典问答网
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  数学问题概率求解释Reworkproblem28fromsection3.4ofyourtext,involvingthedrawingoftwoballsfromaboxofcoloredballs.Assumetheboxcontains8balls:3red,3blue,and2yellow.Aballisdrawnanditscolornoted.Ifthebal

  数学问题概率求解释

  Reworkproblem28fromsection3.4ofyourtext,involvingthedrawingoftwo

  ballsfromaboxofcoloredballs.Assumetheboxcontains8balls:

  3red,3blue,and2yellow.Aballisdrawnandits

  colornoted.Iftheballisyellow,itisreplaced;otherwise,itisnot.

  Asecondballisthendrawnanditscolorisnoted.

  Whatistheprobabilitythatthefirstballwasyellow,giventhatthe

  secondwasred?

  KEYIS7/27

  Anyoneknowthedetailedprocess?

  Thax!

1回答
2020-03-17 11:04
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寇东升

  首先算出来取出第二个求是红球的概率:3/8*2/7+3/8*3/7+2/8*3/8=81/(28*8)

  再算出第一次取出黄球第二次取出红球的概率:2/8*3/8=6/(8*8)

  6/(8*8)除以81/(28*8)就是7/27

  ps:中间数字太大我就没算结果了

2020-03-17 11:06:40

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