Question from http://www.sgforums.com/forums/2297/topics/302719
Five married couples are to be seated in a row of 10 adjacent seats for a concert. In how many ways can they be seated if all the men sit in a group while all the women sit together given that no husband sit next to his wife.
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Answer:
For:
M M M M M F F F F F
The number of combinations is 5! × 5! × 2 = 28800 ways
For:
M M M M couple F F F F
The number of combinations is 4! × 4! × (2 × 5) (choice of couples) = 5760 ways
Hence, answer is 28800 - 5760 = 23040 ways
