Two trains, each 100 meters long, moving in opposite directions, completely pass each other in 20 seconds. If one train is moving twice as fast the other, then what is the speed of the faster train (in km/hr)? Pick one.
A) 16 km/hr
B) 20 km/hr
C) 24 km/hr
D) 28 km/hr
E) 32 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)/20 = 3x   x = 10/3 m/s   So, the speed of the faster train is 20/3 = 20/3 * 18/5= 
<gadget id="calculator">20/3 * 18/5</gadget>
<output>24</output>
24 km/hr   The answer is 24 km/hr.
<result>C</result>
Two trains, each 100 meters long, moving in opposite directions, completely pass each other in 20 seconds. If one train is moving twice as fast the other, then what is the speed of the faster train (in km/hr)?