Henry Ernest Dudeney/Modern Puzzles/43 - The Two Ships

by : $43$

 * The Two Ships
 * A correspondent asks the following question.


 * Two ships sail from one port to another -- $200$ nautical miles -- and return.
 * The Mary Jane travels outwards at $12$ miles an hour and returns at $8$ miles an hour,
 * thus taking $41 \tfrac 2 3$ hours on the double journey.
 * The Elizabeth Ann travels both ways at $10$ miles an hour, taking $40$ hours on the double journey.


 * Now, seeing that both ships travel at the average speed of $10$ miles per hour, why does the Mary Jane take longer than the Elizabeth Ann?


 * Perhaps the reader could explain this little paradox.