Traveller Comedy

A traveller walking along a road asked an old man working in a field as to how long it would take to get to the next village. The old man did not answer, so the stranger went on his way. He had not gone far when he heard a call : “Hi, mister, come back. ”The traveller returned and the old man said, “It’ll take you about 20 minutes”. “Why didn't you tell me that when I asked you?” asked the traveller. “How did I know how fast you were going to walk?” replied the old man.