Question 400978
Imagine that the front of the train is just entering the tunnel.
You want to know how far the end of the train has to go to
get to the other end of the tunnel.
The 2 mile long train has to go 2 miles for the back end to reach the
beginning of the tunnel. Then the train has to go another mile
for the back end of the train to reach the other end of the tunnel
So, the train has to go 3 miles.
{{{3 = 12*t}}}
{{{t = 1/4}}} hr
The train takes 15 min to completely go through the tunnel