A train that is 1 mile long starts through a tunnel that is also 1 mile long. The train is traveling 15 miles per hour. How long does it take for the train to get completely out of the tunnel?

3 answers

Use this proportion. Cross multiply and solve for x -- the time it takes the front of the train to go through the tunnel.

15/60 = 1/x
15x = 60
x = 60/15 = 4 minutes for the front of the train to go through the tunnel.

It takes the rear of the train the same time.

7.5 min