Four children — A, B, C, and D — are going to sit in four chairs in a row. Child C must be somewhere to the left of child D. How many possible configurations are there for the children?
Pick one
A) 6  B) 12  C) 18  D) 24  E) 30
The number of ways to seat 4 people is 4! = 24.   Child C will sit to the left of Child D in exactly half of these arrangements.   The total number of possible arrangements is 24/2= 
<gadget id="calculator">24/2</gadget>
<output>12</output>
12   The answer is 12.
<result>B</result>
Four children — A, B, C, and D — are going to sit in four chairs in a row. Child C must be somewhere to the left of child D. How many possible configurations are there for the children?