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Mathematics 9 Online
OpenStudy (lgbasallote):

Five Americans, three Italians and six French sit randomly in a round table such that each sits together with their countrymen. How many seating arrangements are possible?

OpenStudy (lgbasallote):

would it be 5!3!6!

OpenStudy (lgbasallote):

i think that would be how it would be if they were in a row....

OpenStudy (lgbasallote):

so maybe the two ends of the row would have the same nationality?

OpenStudy (anonymous):

am i making u nervous by watching you lol

OpenStudy (lgbasallote):

not really..no...

OpenStudy (lgbasallote):

you do make me creeped out though....

OpenStudy (anonymous):

its in a cirlce so you have to restrict..different than in a row

OpenStudy (lgbasallote):

...but 5!3!6! is for the row right?

OpenStudy (lgbasallote):

ahh i got it 4!3!6! + 5!2!6! + 5!3!5!

OpenStudy (anonymous):

for the row?

OpenStudy (lgbasallote):

circle

OpenStudy (lgbasallote):

hmm no that's not it

OpenStudy (anonymous):

hmm..i dont think that it is that easy.

OpenStudy (anonymous):

okay so you have to fix one person first..then arrange the others

OpenStudy (lgbasallote):

that's why i used what i wrote a while ago...

OpenStudy (anonymous):

but it didnt look right..hang on..lemme try

OpenStudy (lgbasallote):

yes it wasn't

OpenStudy (lgbasallote):

it's too small

OpenStudy (lgbasallote):

it's not 5!3!6! + 4!3!6! + 5!2!6! + 5!3!5! either

OpenStudy (lgbasallote):

the number of ways to arrange n objects in a circle is (n-1)!

OpenStudy (anonymous):

i think you have to do it in cases. that is correct...but your question you have to arrange the 3 nationalities hmm..

OpenStudy (lgbasallote):

i think this is more difficult than how i make it out to be

OpenStudy (anonymous):

do they alternate?

OpenStudy (lgbasallote):

i don't think so

OpenStudy (anonymous):

like AAIIFF.. or AAAIIIFFF

OpenStudy (lgbasallote):

i now have no idea how to do this

hartnn (hartnn):

taking each nationality group as 1 entity , those 3 entities can be arranges in 2! ways(in circle) , so wouldn't it be simply 2!(5!3!6!)

OpenStudy (lgbasallote):

....that's right.....

OpenStudy (lgbasallote):

what did you do?

OpenStudy (lgbasallote):

explain what happened please @hartnn

hartnn (hartnn):

lol! i think u understand how n people can be arranged in (n-1)! ways in circular fashion.....or u need to understand that ?

OpenStudy (lgbasallote):

i assume it's because one can sit on the top and then (n-1)! is the permutation the others can sit on the remaining seats

hartnn (hartnn):

on the top ?? take 3 people, how many ways can they sit in circular fashion ? 2 ? or more ?|dw:1348727561739:dw|

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