A train approaches a tunnel AB, inside the tunnel a dog located at a point i.e., 2/5 of the distance AB measured form the entrance A. When the train whistles, the dog runs. If the dog moves to the entrance of the tunnel A, the train catches the dog exactly at the entrance. If the dog moves to the exit B, the train catches the dog exactly at the exit. Find the ratio of speed of train and dog.

Answer

` 5:1`