Two bullet train s are running in opposite directions with the same speed. If the length of each bullet train is 120 metres and they cross each other in 12 seconds, then the speed of each bullet train (in km/hr) is:
Select
A) 46 km/hr.  B) 36 km/hr.  C) 56 km/hr.  D) 76 km/hr.  E) 66 km/hr.
B   36 km/hr.   Let the speed of each bullet train be x m/sec.   Then, relative speed of the two bullet train s = 2x m/sec.   So, 2x = (120 + 120)/12   --&gt; 2x = 20   --&gt; x = 10.   --&gt; Speed of each bullet train = 10 m/sec = 10 x 18/5 km/hr = 36 km/hr.
<result>B</result>
Two bullet train s are running in opposite directions with the same speed. If the length of each bullet train is 120 metres and they cross each other in 12 seconds, then the speed of each bullet train (in km/hr) is: