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Problem 1.
Two boys were walking through a narrow railroad tunnel that was
exactly one mile long.
The tunnel had distance markers every tenth of a mile, and just as they got
to the 0.6 mile marker, they heard a train whistle from the direction they
were walking. Both boys immediately started running in opposite directions.
One boy ran in the direction of the train because the mouth of the tunnel was
closer (0.4 miles) in that direction. The other boy ran away from the train
toward the end of the tunnel which was 0.6 miles away. Each boy ran 10 miles
per hour. As it turned out the boy who ran toward the train got to the mouth
of the tunnel at the same time the train entered the tunnel and was barely
able to jump out of the way. The boy who ran away from the train reached the
end of the tunnel at the same time as the train reached the end of the tunnel
and was also barely able to jump out the way. How fast was the train going?
Solution:
 distance = (speed)(time)
 (1)
d = (x)(0.04)
 (2) d + 1 mile
= (x)(0.06)
Subtract (1) from (2) to get 1
= 0.02x
=> x = 50 mph
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