Two trains, each 100 m long, moving in opposite directions, cross other in 6 sec. If one is moving twice as fast the other, then the speed of the faster train is?  Choose the correct choice from the following answers:
A) 26 km/hr  B) 17 km/hr  C) 90 km/hr  D) 77 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)/6 = 3x =&gt; x = 25/2.   So, speed of the faster train = 50/2 = 50/2 * 18/5= 
<gadget id="calculator">50/2 * 18/5</gadget>
<output>90</output>
90 km/hr.   Answer:90 km/hr
<result>C</result>
Two trains, each 100 m long, moving in opposite directions, cross other in 6 sec. If one is moving twice as fast the other, then the speed of the faster train is?