The Brain Teaser: Scroll Down for your Solution
Matthew walks up and down a hill which is three kilometers each way. His dog, being slower, walks at half the speed. When Matthew reaches the top of the hill he turns around and walks down to meet his dog part way. Matthew continues walking to the bottom of the hill maintaining his speed. The dog follows him, also maintaining his speed. How far does the dog walk?
Four kilometers. When Matthew reaches the top of the hill, he will have walked three kilometers, and his dog will be half-way, or 1.5 kilometers. Matthew then turns around and walks back, but his dog continues walking up the hill until they meet. They will meet at the two kilometer point. The dog will turn around at this point and follow Matthew down the hill completing a 4 kilometer walk.