Two trains, each 100 meters long, moving in opposite directions, completely pass each other in 12 seconds. If one train is moving twice as fast the other, then what is the speed of the faster train (in km/hr)?	Answers:
A) 36 km/hr
B) 40 km/hr
C) 44 km/hr
D) 48 km/hr
E) 52 km/hr
Let the speed of the slower train be x m/s   Then, the speed of the faster train is 2x m/s   The relative speed is 3x m/s   (100 + 100)/12 = 3x   x = 50/9   So, the speed of the faster train is 100/9 = 100/9 * 18/5= 
<gadget id="calculator">100/9 * 18/5</gadget>
<output>40</output>
40 km/hr   The answer is 40 km/hr.
<result>B</result>
Two trains, each 100 meters long, moving in opposite directions, completely pass each other in 12 seconds. If one train is moving twice as fast the other, then what is the speed of the faster train (in km/hr)?