新GRE数学应试技巧:排列

2011-11-21 04:48:37
2011新gre考试实施以来,不仅对写作部分茫然不知所措,就连我们所擅长的数学也甚是担忧,相信这其中的原因还是由于考生在新gre数学复习时没有把基础打牢。如果新版gre数学基本考点都没有复习到,如何能拿到分数呢?所以说,想要新版gre数学考好,复习的时候一定要把基本概念和重要考点都弄扎实。

  Permutation of Objects

  The number of ways n distinct objects can be ordered is n!.

  Example:

  Number of ways 6 people can from a queue is 6!.

  Number of ways 5 different cars can be parked in 5 parking spaces is 5!.

  Remember:

  This does not apply if there are identical objects or ordering does not matter.

  Permutation with Selection

  The number of ways n objects drawn from a collection of m distinct objects can be ordered is m!/(m-n)!.

  Example:

  Number of ways a queue of length 3 can be formed from a group of 5 people is 5!/(5-3)!=5!/2!=5*4*3=60.

  Number of possible top ten list for 150 movies is 150!/(150-10)!.

  Remember:

  This does not apply if there are identical objects or ordering does not matter.

  由于美国数学基础教育的难度增加导致数学考试越来越难,但新gre数学复习考点都是高中时候学到的知识点,考生不要过于紧张,把基本概念弄明白,再记住一些新版gre数学必备的词汇,那么相信新版gre数学应该没有问题。

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