Smilebuffalo
Member
In how many ways can 8 girls be divided into 4 sets of 2? (answer = 105)
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odd question - combinations (1 Viewer)
- Thread starter Smilebuffalo
- Start date
scardizzle
Salve!
Not exactly sure why this is right but the reasoning is that you are implying an order so you divide by 4 factorial. Don't really understand the concept too well my self.
8C2 x 6C2 x 4C2 x 2C2 *1/4!
=105
EDIT: i think this is why you divide by 4!
consider abcdef
in order to arrange these in to to 3 sets of 2 i calculate:
6C2 x 4C2 x 2C2
but this solution counts these as seperate cases:
ab cd ef
ef cd ab
etc.
therefore we divide by 3! in this case
and 4! in your question
8C2 x 6C2 x 4C2 x 2C2 *1/4!
=105
EDIT: i think this is why you divide by 4!
consider abcdef
in order to arrange these in to to 3 sets of 2 i calculate:
6C2 x 4C2 x 2C2
but this solution counts these as seperate cases:
ab cd ef
ef cd ab
etc.
therefore we divide by 3! in this case
and 4! in your question
Last edited: