Two trains 250 m and 500 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?	Select.
A) 10.6 B) 10.9 C) 10.4 D) 27 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 = 250 + 500= 
<gadget id="calculator">250 + 500</gadget>
<output>750</output>
750 m.   Required time= 750 * 9/250= 
<gadget id="calculator">750 * 9/250</gadget>
<output>27</output>
27 sec   Answer: 27
<result>D</result>
Two trains 250 m and 500 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?