Henry Ernest Dudeney/Modern Puzzles/45 - The Man and the Dog

by : $45$

 * The Man and the Dog
 * "Yes, when I take my dog for a walk," said a mathematical friend, "he frequently supplies me with some interesting problem to solve.
 * One day, for example, he waited, as I left the door, to see which way I should go,
 * and when I started he raced to the end of the road, immediately returning to me;
 * again racing to the end of the road and again returning.
 * He did this four times in all, at a uniform speed,
 * then ran at my side the remaining distance, which according to my paces measured $27$ yards.
 * I afterwards measured the distance from my door to the end of the road and found it to be $625$ feet.


 * Now, if I walk $4$ miles per hour, what is the speed of my dog when racing to and fro?"