Two trains 300m and 400m long run at the speed of 36kmph and 18 kmph in opposite directions in parallel tracks. The time which they take to cross each other is?  Pick.
A) 5.6sec
B) 46.67 sec
C) 10.8sec
D) 12.6sec
E) 15sec
Relative speed = 36+18= 
<gadget id="calculator">36+18</gadget>
<output>54</output>
54 kmph * 5/18= 15 m/s   Distance covered in crossing each other = 300+400= 
<gadget id="calculator">300+400</gadget>
<output>700</output>
700m   Required time= 700*1/15=46.67 sec   Answer is 46.67 sec
<result>B</result>
Two trains 300m and 400m long run at the speed of 36kmph and 18 kmph in opposite directions in parallel tracks. The time which they take to cross each other is?