Two trains 140 m and 160 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 one
A) 10 B) 11 C) 12 D) 10.8 E) 13
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 = 140 + 160= 
<gadget id="calculator">140 + 160</gadget>
<output>300</output>
300 m.   Required time= 300 * 9/250 = 54/5= 
<gadget id="calculator">54/5</gadget>
<output>54/5 = around 10.8</output>
10.8 sec.   Answer: Option 10.8
<result>D</result>
Two trains 140 m and 160 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?