A group of seven people quene up to enter into a museum. It is given that Cherry and Rainbow are two of them.
(a) If Cherry must be the first one and Rainbow must be the last one, how many arrangement are there?
(b) If Cherry and Rainbow must be arranged at the two ends, how many arrangements are there?
(c) If Cherry cannot be the first one and Rainbow cannot be the last one, how many arrangements are there?
F.5 combination&permutation
2011-04-03 2:32 am
回答 (1)
2011-04-03 2:55 am
✔ 最佳答案
(a) 5!=720(b) 5!*2=1440
(c) 6!*6!=518400
收錄日期: 2021-04-13 17:53:46
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https://hk.answers.yahoo.com/question/index?qid=20110402000051KK00887