SOLUTION: A train that is x meters long takes 30 seconds fro the time it first enters a tunnel that is 400 m long, until it is completely through the tunnel. A stationary ceiling light in th
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Question 1095003: A train that is x meters long takes 30 seconds fro the time it first enters a tunnel that is 400 m long, until it is completely through the tunnel. A stationary ceiling light in the tunnel is directly above the train for 10 seconds. Find the value, in meters, of x. Answer by ikleyn(52790) (Show Source):
From the condition, the train' speed (rate) is meters per second.
To go completely through the tunnel, the train must move forward for the length 400+x meters.
It takes exactly 30 seconds, so the distance it moves forward for this time is
Rate*Time = = 3x.
So, your equation is
400+x = 3x, (saying that the two distances are the same)
400 = 2x ====> x = = 200 meters.
Answer. The train is 200 meters long.
There is a bunch of lessons "on the train", as a part of Travel and Distance problems.
