At a dinner party 5 people are to be seated arround a circular table. Tow seating arrangemets 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?
5 people in a row will sit in 5*4*3*2*1 ways = 120 ways.
In circle, abcde = bcdea = cdeab = deabc = eabcd. So each different arrangement (by people's respective position) is actually reprsented 5 times in this 120. So divide by 5 and you get 24.
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发表于 2011-3-13 13:56:39
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