Two rhinos are charging towards each other from a distance of 100 metres apart. They are travelling at 5 metres per second.
A fly starts from the horn of one of the rhinos and flies directly to the horn of the other rhino at a speed of 12 metres per second. When it arrives it immediately turns and flies back to the horn of the other rhino and repeats this behaviour until the two rhinos collide.
How far does the fly travel during this time?
An efficient, elegant method is required to solve this problem.
