Two trains of length 200 m and 100 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 18 kmph and 36 kmph. After how much time will the trains meet? Pick one
A) 27/7 sec
B) 20/3 sec
C) 33/7 sec
D) 21/7 sec
E) 32/7 sec
They are moving in opposite directions, relative speed is equal to the sum of their speeds.   Relative speed = (18 + 36)*5/18 = 3*5= 
<gadget id="calculator">3*5</gadget>
<output>15</output>
15 mps.   The time required= d/s = 100/15 = 20/3 sec.   Answer : 20/3 sec
<result>B</result>
Two trains of length 200 m and 100 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 18 kmph and 36 kmph. After how much time will the trains meet?