Problem:

Two trains enter a tunnel 200 miles long, traveling at 100 mph at the same time from opposite directions. As soon as they enter the tunnel a supersonic bee flying at 2000 mph starts from one train and heads toward the other one. As soon as it reaches the other one it turns around and heads back toward the first, going back and forth between the trains until the trains collide in a fiery explosion in the middle of the tunnel. How far did the bee travel?

Solution:

This puzzle is a little tricky one. One’s thinking about solving this problem goes like this “ok, so I just need to sum up the distances that the bee travels…” but then you quickly realize that its a difficult summation.

The tunnel is 200 miles long. The trains meet in the middle traveling at 100 mph, so it takes them an hour to reach the middle. The bee is traveling 2000 mph for an hour (since its flying the whole time the trains are racing toward one another) – so basically the bee goes 2000 miles.

 

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