SOLUTION: Four couples are seated on a bench. Find the number of ways a particular couple must: a. Sit together b. Not sit together

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Question 1135864: Four couples are seated on a bench. Find the number of ways a particular couple must:
a. Sit together
b. Not sit together
Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
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Four couples are seated on a bench. Find the number of ways a particular couple highlight%28cross%28must%29%29 can: 

(a)  Sit together.         ANSWER :  2*((4-1)*2+1)! = 2*7! = 2*5040 = 10080.



(b)  No sit together.      ANSWER :  8! - 10080 = 30240.

                                     The complement set to (a).