Two trains of length 100 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?
Pick one.
A) 6 B) 7 C) 9 D) 2 E) 10
Relative speed = (54 + 90)* 5/18= 
<gadget id="calculator">(54 + 90)* 5/18</gadget>
<output>40</output>
40 mps.   The time required= d/s = (100 + 100 + 200)/40   = 400/40= 
<gadget id="calculator">400/40</gadget>
<output>10</output>
10 sec.   Answer:10
<result>E</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 54 kmph and 90 kmph. In how much time will the trains cross each other?