Two trains start at the same time, one from London to Liverpool, the other from Liverpool to London. If they arrive at their destinations one hour and four hours respectively after passing one another, how much faster is one train running than the other?
If you have not tried to solve it, have a go now. For everyone else, the answer is after the break.
The solution is that one train was running twice as fast as the other. But who can come up with the simplest way of explaining why this was the case? Go for it!
I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.