Question

Two hunters started to walk towards each other simultaneously from two different locations in the forest. The distance between them was 21 miles. The first hunter walked at a rate of 4 mph, while the second one walked at a rate of 3 mph. The first hunter took a dog with him, who ran at an average rate of 5 mph. The dog started to run towards the second hunter, met him and ran back to the first hunter. The dog repeated this until the two hunters met each other. How many miles did the dog run?

Answer 1

The dog ran 15 miles

Explanation:

The combined speed of the 2 hunters is 7mph, therefore, they will met in 21/7 = 3 hours, becuse they are walking in opposite directions. In this 3 hours the dog kept running and thus it ran 3*5 = 15 miles. Note that the position of the dog is always between the position of both hunters, therefore when both hunters met each other, the dog will be alredy there.