A person has his own coach&. Whenever he goes to railway station he takes his coach. One day he was supposed to reach the railway station at 5 O'clock. But he finished his work early and reached at 3 O'clock. Then he rung up his residence and asked to send the coach immediately. He came to know that the coach has left just now to the railway station. He thought that the coach has left just now to the railway station. He thought that he should not waste his time and started moving towards his residence at the speed of 3 miles/hr. On the way, he gets the coach and reaches home at 6 o'clock. How far is his residence from railway station.