Two trains 200 m and 300 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?
Choose the correct choice from the following answers:
A) 18
B) 10.9
C) 10.4
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 + 300= 
<gadget id="calculator">200 + 300</gadget>
<output>500</output>
500 m.   Required time= 500 * 9/250= 
<gadget id="calculator">500 * 9/250</gadget>
<output>18</output>
18 secs   18nswer: 18
<result>A</result>
Two trains 200 m and 300 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?