A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is:

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Question: A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is:
[A].

130

[B].

360

[C].

500

[D].

540

Answer: Option C

Explanation:

Speed = 78 x 5 m/sec = 65 m/sec.
18 3

Time = 1 minute = 60 seconds.

Let the length of the tunnel be x metres.

Then, 800 + x = 65
60 3

3(800 + x) = 3900

x = 500.