If a train is going at a speed of 30 mph, and takes two minutes to go through a tunnel 9 times as long as the train, how long is the train?
(1/30 h)* 30 mi/h = distance travelled in 2 minutes = 1 mile
When going through a tunnel 9 times as long as the train, the trail travels 10 train lengths. (Additional time is needed to get its entire length past the exit).
Therefore the train is 1/10 mile long