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Newbie | Next Rank: 10 Posts
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by psburn » Fri Oct 10, 2008 6:57 am
In how many ways can a lawn tennis mixed double be made from seven married couples if no husband and wife play in the same set?
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by kris610 » Fri Oct 10, 2008 7:19 am
I believe it is 21. You may form 42 possible pairs, but since we are considering combinations here, you should divide this by 2!.
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by psburn » Fri Oct 10, 2008 9:22 pm
The correct answer is 840.... :roll:
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by mental » Sat Oct 11, 2008 7:15 am
seven couples, and if one is selected - then spouse can not be selected

so in turn we are talking about 7 entities only

7P4 = 840

1st place: 7
2nd place: 6
3rd place: 5
4th place: 4

=7*6*5*4=840
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