Two trains of length 300 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 54 kmph and 90 kmph. In how much time will the trains cross each other?  Select:
A) 87/7 sec B) 80/7 sec C) 80/9 sec D) 80/5 sec E) 15 sec
Relative speed = (54 + 90)* 5/18 = 8 * 5= 
<gadget id="calculator">8 * 5</gadget>
<output>40</output>
40 mps.   The time required= d/s = (100 + 300 + 200)/40   = 600/40= 
<gadget id="calculator">600/40</gadget>
<output>15</output>
15 sec.   Answer: 15 sec
<result>E</result>
Two trains of length 300 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 54 kmph and 90 kmph. In how much time will the trains cross each other?