Two stations A and B are separated by a distance that takes 24 hours to traverse by train. Every hour, on the hour, a train leaves from Station A for Station B and from Station B for Station A. In other words, in a 24-hour period, twenty-four trains leave each station at 1-hour intervals at exactly the same time from each station, bound for the other. If you are a passenger going from Station A to Station B in one of these trains, how many trains will you meet coming the other way?
Solution: When you start your journey, there are already 24 trains on their way towards you and during your journey, another 24 trains will leave Station B towards Station A. Hence you will meet 48 trains in total, the first will just be arriving when you embark and the second pulling out of the station as you reach your destination.