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标题: Prep PS1 77 [打印本页]

作者: girlwithwings 时间: 2010-7-9 14:11
标题: Prep PS1 77
77.
At a dinner party, 5 people are to be seated around a circular table.Two seating arrangements are considered different only when the positions of the people are different relative to each other. What is the total number of different possible seating arrangements for the group?

(A) 5

(B) 10

(C) 24

(D) 32

(E) 120

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【答案】C

我的计算是P(4,4) = 24 ，就是相对于5人当中的1人，其余4人全排列。

从以上计算来看，ABCDE 这种排列和AEDCB这种排列是不一样的，但是他们相邻的人确是一样的，只是改变左右位置而已。

这里有个疑问：ABCDE和AEDCB是否重复？如何理解这句话 the positions of the people are different relative to each other

作者: girlwithwings 时间: 2010-7-12 13:37
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