Two trains of length 100 meters and 200 meters are 450 meters apart. They are moving towards each other on parallel tracks, at speeds of 90 km/h and 72 km/h. After how many seconds will the trains meet?
Options.
A) 6  B) 8  C) 10  D) 12  E) 14
The speeds are 90000/3600= 
<gadget id="calculator">90000/3600</gadget>
<output>25</output>
25 m/s and 72000/3600= 
<gadget id="calculator">72000/3600</gadget>
<output>20</output>
20 m/s   The relative speed is 45 m/s.   time= 450 / 45= 
<gadget id="calculator">450 / 45</gadget>
<output>10</output>
10 seconds   The answer is 10.
<result>C</result>
Two trains of length 100 meters and 200 meters are 450 meters apart. They are moving towards each other on parallel tracks, at speeds of 90 km/h and 72 km/h. After how many seconds will the trains meet?