Two trains of length 100 m and 200 m are 100 m apart. They start moving towards each other on parallel tracks, at speeds 90 kmph and 72 kmph. In how much time will the trains cross each other?
Select:
A) 80/6	B) 80/7	C) 80/9	D) 80/2	E) 80/1
Relative speed = (90 + 72)* 5/18= 
<gadget id="calculator">(90 + 72)* 5/18</gadget>
<output>45</output>
45 mps.   The time required= d/s = (100 + 100 + 200)/45   = 400/45 = 80/9 sec.   Answer:80/9
<result>C</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 90 kmph and 72 kmph. In how much time will the trains cross each other?