Nine children — A, B, C, D, E, F, G, H, and I — are going to sit in nine chairs in a row. Child C must be somewhere to the left of child D. How many possible configurations are there for the children? Choose the correct answer.
A) 155,880 B) 164,770 C) 173,660 D) 181,440 E) 192,550
The number of ways to seat 9 people is 9! = 362,880.   Child C will sit to the left of Child D in exactly half of these arrangements.   The total number of possible arrangements is 362,880/2 = 181,440   The answer is 181,440.
<result>D</result>
Nine children — A, B, C, D, E, F, G, H, and I — are going to sit in nine chairs in a row. Child C must be somewhere to the left of child D. How many possible configurations are there for the children?