SOLUTION: Seven people line up for a photo. How many different line ups are possible if 2 people refuse to sit together?
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Question 444697: Seven people line up for a photo. How many different line ups are possible if 2 people refuse to sit together? Answer by robertb(5830) (Show Source):
You can put this solution on YOUR website! Count the total number of ways the two people SIT TOGETHER. This 2!6!
Subtract from the total number of ways 7 people can line up. This is 7!
Hence 7! - 2!6! = 3600 ways.
