AVERAGE SPEED.
(
Money Puzzles)
In a recent motor ride it was found that we had gone at the rate of ten
miles an hour, but we did the return journey over the same route, owing
to the roads being more clear of traffic, at fifteen miles an hour. What
was our average speed? Do not be too hasty in your answer to this simple
little question, or it is pretty certain that you will be wrong.
Answer:
The average speed is twelve miles an hour, not twelve and a half, as
most people will hastily declare. Take any distance you like, say sixty
miles. This would have taken six hours going and four hours returning.
The double journey of 120 miles would thus take ten hours, and the
average speed is clearly twelve miles an hour.
