Trains Q40

40.	Two trains, each 100 m long, moving in opposite directions, cross each other in 8 seconds. If one is moving twice as fast the other, then the speed of the faster train is:
	A. 30 km/hr B. 45 km/hr C. 60 km/hr D. 75 km/hr

Answer: Option C

Explanation:

Let the speed of the slower train be x m/sec.

Then, speed of the faster train = 2x m/sec.

Relative speed = (x + 2x) m/sec = 3x m/sec.

	(100 + 100)	= 3x
	8

 24x = 200

x =	25	.
	3

So, speed of the faster train =	50	m/sec
	3

=		50	x	18	km/hr
		3		5

   = 60 km/hr.