A train leaves Station A heading East at 60 mph. One hour later, a second train leaves Station A heading East on a parallel track at 90 mph. How many hours after the second train departs will both trains be side-by-side?
2 hours
When the second train departs, the first train is already 60 miles ahead. The second train gains on the first at a relative speed of 30 mph (90 mph - 60 mph). Closing a 60-mile gap at 30 mph takes exactly 2 hours.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Easy. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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