Two trains 200m and 160m long run at the speed of 68kmph and 40kmph in opposite directions in parallel tracks. The time which they take to cross each other is? Answers: A) 5.6sec B) 8.9sec C) 10.8sec D) 12 sec E) 15sec
Relative speed = 68+40= 
<gadget id="calculator">68+40</gadget>
<output>108</output>
108kmph * 5/18= 30 m/s   12 secistance covered in crossing each other = 200+160= 
<gadget id="calculator">200+160</gadget>
<output>360</output>
360m   Required time= 360*1/30= 
<gadget id="calculator">360*1/30</gadget>
<output>12</output>
12 sec   Answer is 12 sec
<result>D</result>
Two trains 200m and 160m long run at the speed of 68kmph and 40kmph in opposite directions in parallel tracks. The time which they take to cross each other is?