Two trains of length 100 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 36 kmph and 72 kmph. In how much time will the trains cross each other? Choose the most appropriate option
A) 40/6
B) 40/3
C) 40/9
D) 40/2
E) 40/1
Relative speed = (36 + 72)* 5/18= 
<gadget id="calculator">(36 + 72)* 5/18</gadget>
<output>30</output>
30 mps.   The time required= d/s = (100 + 100 + 200)/30   = 400/30 = 40/3 sec.   Answer:40/3
<result>B</result>
Two trains of length 100 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 36 kmph and 72 kmph. In how much time will the trains cross each other?