combinatorics/probability
posted by Anonymous on .
Can't figure this problem out... wasn't great at the combinatorics unit, then it turns out everything carries over to probability.
five couples attend a bridge party, including mr. and mrs. smith. they are randomly assigned partnership pairs.
1. probability mr. smith will have mrs. smith has a partner?
2. probability all five couples will be partners?
thanks!

Hmmmm. Randomly assigned parteners? Does that mean Mr Smith can get Mr Jones as a partner? The problem says randomly, so I assume same gender couples are ok.
1. (1/9) if same gender couples are ok.
2) (1/9)(1/7)(1/5)(1/3) check that thinking.
Now, if same gender are not allowed..
1) 1/5
2) 1/5* 1/4*1/3 * 1/2
check that.