I tried to first finding the probability that only one couple sits together (9x2!8!) then two couples (25x2!2!2!6!) then three (22x3!2!2!2!4!) then four (14x4!2!2!2!2!) then five (5!x2!2!2!2!2!)
I think I would then use the inclusion exclusion principle and divide by 10! to find the probability, but I've never used it with five items. Am I on the right track? How would I finish this?
Thank you so much!