How many different ways can a group of 8 be divided into 4

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How many different ways can a group of 8 be divided into 4 [#permalink]

22 Jan 2006, 09:48

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How many different ways can a group of 8 be divided into 4 teams of 2 people?

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22 Jan 2006, 09:57

the number of ways we can select 2 people from 8 =>2C8=28
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22 Jan 2006, 10:12

Ways of selecting first team:

8C2 = 28

2nd team: 6C2 = 15

3rd team: 4C2 = 6

4th team: 2C2 = 1

Therefore, using the multiplication principle, the total number of ways =

28 X 15 X6 X 1 = 2520

However, order of selection does not matter, hence we must divide
this number by the factorial of the number of teams...

Answer = 2520/4! = 105

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23 Jan 2006, 22:50

21stCenturion wrote:

had this problem always when do i add n when do i multiple.. pls someone explain!
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25 Jan 2006, 01:47

I made the same mistake as Andy did.Can someone explain when to add and miltiply..would be helpful

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25 Jan 2006, 07:37

can someone explain this?

Quote:

However, order of selection does not matter, hence we must divide
this number by the factorial of the number of teams...

Answer = 2520/4! = 105

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28 Jan 2006, 21:54

# of ways to get teams of 2 people from a group of 8 peopele = 8C2 = 8!/2!6! = 28

[#permalink] 28 Jan 2006, 21:54

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How many different ways can a group of 8 be divided into 4

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How many different ways can a group of 8 be divided into 4

How many different ways can a group of 8 be divided into 4

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