来自《耶鲁大学开放课程：金融理论 第8集 第8集》

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  so it looks like that's what you'd get if you had 200
  如果你有200的话看起来像
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  dollars, but at the end,
  你能获得的 但是最终
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  as he's saying, you're only going to get 110
  就像他说的 你只能得到110
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  and not 210.
  而不是210
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  So this present value of this thing has to be less than 200.
  这个的现值应该低于200
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  So if you double the coupon--if you halve the interest rate,
  如果你把付息加倍 如果你知道利率
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  the interest rate was originally 10 percent,
  开始利率是百分之十
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  if you cut the interest rate in half to 5 percent it looks like
  如果把利率见到百分之五
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  your annual coupon is double the interest rate,
  看起来你的年付息是利率的两倍
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  but at the end you don't get principal that's double the
  最后你拿到本金
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  original principal.
  是原始本金的两倍
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  All you did was double--relative to the interest
  所有都是加倍 相对于