Trains Q47

47.	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.