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PS Problem

by antimatter1 » Fri May 15, 2009 7:54 am
5 people are seated around a round 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?

What's the best way to tackle this (not wasting time on writing out all the possibilities)?

Thanks!
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by mike22629 » Fri May 15, 2009 8:43 am
5!/5

Is answer 24?
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by antimatter1 » Fri May 15, 2009 9:47 am
Yes it is.
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by silentdud » Fri May 29, 2009 12:29 pm
Why are you dividing by five? I understand the basic logic behind the five factorial, but how does the division keep instances from repeating?
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by Svedankae » Wed Jun 03, 2009 10:13 am
silentdud wrote:Why are you dividing by five? I understand the basic logic behind the five factorial, but how does the division keep instances from repeating?
I initially thought its 5! but now realized that this cant be the case. However, I too, like silentdud, dont understand why you divide by 5. Is there a formula or something?

Thanks a bunch.
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by vinayakdl » Wed Jun 03, 2009 11:40 am
This has to do with Circular arrangement. When you have 5 people in a line 5! works but when you have a round table AB and BA are the same.
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by tdadic84 » Wed Jun 03, 2009 11:48 am
the actual formula is n!-1!

so 5 people would be 5!-1! = 4! = 24

I know that 5!/5 worked, but the above is the proper formula...
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by vinayakdl » Wed Jun 03, 2009 1:11 pm
Did you mean (n-1)!...?
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