Susan, John, Daisy, Tim, Matt, Jane and Kim need to be seated in 7 identical chairs in straight line so that Susan is seated always left to Tim. How many such arrangements are possible ? Choose the correct choice from the following.
A) 36  B) 120  C) 800  D) 2400  E) 2520
Total # of arrangement of 7 people is 7!.   In half of the cases Susan will be seated left to Tim and in half of the cases Susan will be seated right to Tim (why should one seating arrangement have more ways to occur than another?).   So, # of arrangements to satisfy the given condition is 7!/2=2520.   Answer: 2520.
<result>E</result>
Susan, John, Daisy, Tim, Matt, Jane and Kim need to be seated in 7 identical chairs in straight line so that Susan is seated always left to Tim. How many such arrangements are possible ?