来自《耶鲁大学开放课程：博弈论 第9集 第9集》

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  So if Venus chooses left and Serena chooses right,
  如果维纳斯选左而塞丽娜选右
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  then Serena has guessed wrong. Is that correct?
  那么塞丽娜就猜错了方向 没错吧
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  So it's gussed wrong.
  她猜错方向了
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  In which case Venus wins the points 80% of the time
  则此时维纳斯有80%的概率得分
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  and Serena wins it 20% of the time.
  而塞丽娜只有20%能防守得分
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  Conversely, if Venus chooses right and Serena chooses left,
  反过来如果维纳斯选右而塞丽娜选左
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  then again, serena has guessed wrong
  那么塞丽娜又猜错方向了
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  and this time Venus wins the points 90% of the time
  这次维纳斯有90%的概率得分
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  and Serena wins the points 10% of the time.
  而塞丽娜只有10%的概率能防守得分
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  This should be a familiar idea by now,
  至此的内容大家应该都不陌生吧
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  but why is it the case these nineties and eighties are not a 100%?
  那为什么是90%和80%而不是100%呢
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  Why is it the case that if Serena guesses wrong
  为什么如果塞丽娜猜错了方向