At a birthday party, 5 boys and 3 girls are seated around a table.
How many different arrangements are possible if no two girls are seated next to each other?
Normally for these questions rotations are considered to be the same.
Reflections are considered to be different
BUT
Are you interested in gender arangements or individual people arrangements?
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If you are only interested in gender positions then.
Seat a girl first. She is like the begining of the row.
Now there is 5 boys
GBBBBB
We need to slot in 2 more girls
GB*B*B*B*B
The stars indicate where the other 2 girls can go.
4C2 = 6 gender arrangements are possible.
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If you are interested in the position of individuals then
Stil sit any girl first. (could have chosen a boy if you wanted to)
Now there is 5 boys and 2 girls left to seat.
Sit the 5 boys first. This can be done in 5! = 120 ways
So we have GBBBBB and we have to sit 2 more girls.
GB*B*B*B*B
4C2*2 = 12 ways.
So that is 120*12 = 1440 individual child arrangements.
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