Two trains 200 m and 800 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time which they take to cross each other is?  Pick:
A) 10.6
B) 10.9
C) 36
D) 10.8
E) 10.1
Relative speed = 60 + 40= 
<gadget id="calculator">60 + 40</gadget>
<output>100</output>
100 km/hr.= 100 * 5/18 = 250/9 m/sec.   Distance covered in crossing each other = 200 + 800= 
<gadget id="calculator">200 + 800</gadget>
<output>1_000</output>
1000 m.   Required time= 1000 * 9/250= 
<gadget id="calculator">1000 * 9/250</gadget>
<output>36</output>
36 sec.   Answer: 36
<result>C</result>
Two trains 200 m and 800 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time which they take to cross each other is?