# RRB JE exam Mathematics Important MCQs questions solved

Question No: 9

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

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.
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