There are 5 couples. If they will sit 10 chairs in a row such that each couple sits side by side, how many possible cases are there?  Answers:
A) 120  B) 240  C) 1,200  D) 2,460  E) 3,840
Tie the couples. Then we have 5 persons that have to be arranged in 5 places. 5! ways.   Now the couples can change position with each other. 2! ways.   5! * (2!)^2 = 120 *32= 
<gadget id="calculator">120 *32</gadget>
<output>3_840</output>
3840   Answer is E.   5! * 2!= 240 ways.
<result>E</result>
There are 5 couples. If they will sit 10 chairs in a row such that each couple sits side by side, how many possible cases are there?