Two trains, each 100 m long, moving in opposite directions, cross other in 5 sec. If one is moving twice as fast the other, then the speed of the faster train is?
Options:  A) 26 km/hr  B) 17 km/hr  C) 60 km/hr  D) 42 km/hr  E) 46 km/hr
Let the speed of the slower train be x m/sec.   Then, speed of the train = 2x m/sec.   Relative speed = ( x + 2x) = 3x m/sec.   (100 + 100)/5 = 3x =&gt; x = 20/3.   So, speed of the faster train = 40/3 = 40/3 * 18/5   = 42 km/hr.   Answer:42 km/hr
<result>D</result>
Two trains, each 100 m long, moving in opposite directions, cross other in 5 sec. If one is moving twice as fast the other, then the speed of the faster train is?