Permutations and Combinations of ways of dividing into identical and non- identical groups

In how many ways can $8$ people be divided into

1. $4$ groups of $2$ people

2. First pair, second pair. Third pair and the fourth pair

How do you go about doing this question?

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Are you familiar with binomial coefficients? What have you tried? – Jeremy Nov 2 '12 at 9:21

4 groups of 2 people:

  _ _      _ _      _ _      _ _
( 8.7/2! * 6.5/2! * 4.3/2! * 2.1/2! )/4!


First pair, second pair. Third pair and the fourth pair:

1º pair -> 8*7/2! = 28
2º pair -> 6*5/2! = 15
...    ->   ...


understood?

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Use consistent notation, please. – Cameron Buie Nov 2 '12 at 10:53
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