来自《耶鲁大学开放课程：金融理论 第9集 第9集》

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  but we're locking it in today.
  但是是我们在今天协定的
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  So what would we lock in today? How do we compute that?
  所以我们今天会定多少 如何计算呢
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  We already know what that number is. What is it? Yes?
  我们已经知道这个是多少了 请讲
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  Student: It's the ratio of pi 1 over pi 2.
  就是π1比π2的比值
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  Well, I put t here, so something like that.
  这里是T时刻 类似于那个
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  Okay, exactly. That's pi t over pi t plus 1. That's it exactly.
  对完全正确 就是πT/π（T+1）
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  So why is that?
  为什么是这个值呢
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  Student: It's a tradeoff between the dollar t, t plus 1.
  这是T时刻和T+1时刻的一个交易
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  Right, so all we're doing is this forward rate.
  很好 我们所做的就是求远期利率
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  We're exchanging time t dollars for time t plus 1 dollars at this ratio.
  把T时美元和T+1时的按这个比例交易
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  But we're committing to do it today.
  但这是我们在今天完成的
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  But today we already know what the ratio is
  但是我们现在已经求得