SOLUTION: Two escaped convicts are headed east on the railroad tracks. They come to a mile-long tunnel; they have little choice but to enter. They are 0.4 mile into the tunnel when they hear
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Question 736991: Two escaped convicts are headed east on the railroad tracks. They come to a mile-long tunnel; they have little choice but to enter. They are 0.4 mile into the tunnel when they hear an eastbound train closing in on them from behind. Oh no!
Snap decisions are required. The younger, faster convict decides to run the 0.4 mile back out of the tunnel (even though the train is coming at him!). The older and slower convict decides to run the remaining 0.6 mile to the far end of the tunnel. (He will run away from the train because it gives him more time to escape.)
The fast convict runs at 11 miles per hour; the slower convict runs at 7 miles per hour. The train travels at a steady rate. Each man manages to exit the tunnel at the last possible second. Close calls!
Question: what was the speed of the train? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! Two escaped convicts are headed east on the railroad tracks.
They come to a mile-long tunnel; they have little choice but to enter.
They are 0.4 mile into the tunnel when they hear an eastbound train closing in on them from behind. Oh no!
Snap decisions are required.
The younger, faster convict decides to run the 0.4 mile back out of the tunnel (even though the train is coming at him!).
The older and slower convict decides to run the remaining 0.6 mile to the far end of the tunnel.
(He will run away from the train because it gives him more time to escape.)
The fast convict runs at 11 miles per hour; the slower convict runs at 7 miles per hour.
The train travels at a steady rate.
Each man manages to exit the tunnel at the last possible second. Close calls!
Question: what was the speed of the train?
:
Find the time required by the faster guy to get to the near end of the tunnel
.4/11
At this time the train enters the tunnel
The slower guy has traveled 7 * .4/11 = .25454 mi so he is:
.6 - .25454 = .3454 mi to the end of the tunnel
He has to travel .3454 mi while the train travels 1 mile
let t = speed of the train =
Cross multiply
.3454t = 7*1
t =
t = 20.3 mph is the speed of the train
