A mile long train is moving at 60 miles per hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?
For the train to pass completely through the tunnel, it must travel 2 miles.
After 1 mile travel, the train would be completely in the tunnel, and after another mile it would be completely out and since the train is traveling at 1 mile a minute, it will take 2 minutes to pass through the tunnel.