Two trains run in opposite directions on a circular track. Train A travels at a rate of 4 miles per hour and Train B runs at a rate of 6 miles per hour. If the track has a radius of 6 miles and the trains both start from Point S at the same time, how long, in hours, after the trains depart will they again meet at Point S?
Options:
(A) 3
(B) 6
(C) 9
(D) 18
(E) 22 Now, let's think a bit. Some random thoughts:
The trains will travel the perimeter of the circle which is 12 miles. The relative speed of the trains is 2 miles per hour. Time taken to meet = 12/2 = 6 hours
The final answer: (B).