来自《耶鲁大学开放课程：博弈论 第9集 第9集》

• 
  
  Suppose I want to figure out the average height of these three T.A.'s.
  假设我想计算这三位助教的平均身高
• 
  
  So stand up close together so I can at least see what's going on here.
  请站得近一点 这样便于观察
• 
  
  So I think, from where I'm standing,
  从我的观察来看
• 
  
  I've got that Ale is the tallest
  艾尔是最高的
• 
  
  and Myrto is the smallest, is that right?
  米尔托是最矮的 没错吧
• 
  
  So I don't know instantaneously what this average would be,
  我不能马上说出平均身高是多少
• 
  
  but I claim that any weighted average of their three heights,
  但我知道平均身高是一个加权平均数
• 
  
  is going to give me a number that's somewhere
  它一定介于
• 
  
  between the smallest height of the three, which is Myrto's height,
  三人中最矮的米尔托
• 
  
  and the tallest height of the three, which is Ale's height.
  和最高的艾尔的身高之间
• 
  
  Is that right? Is that correct?
  是这样吧
• 
  
  So that's a pretty general idea.
  这是个世人皆知的道理