Concept:When two trains move in the same direction, the relative speed is the difference of their speeds, and the total distance to be covered for overtaking is the sum of their lengths.
Explanation:Step 1: Find the relative speed.
Speed of faster train =
162 km/hr.
Speed of slower train =
36 km/hr.
Since they move in the same direction, relative speed =
162−36=126 km/hr.
Step 2: Convert relative speed from km/hr to m/s.
126 km/hr =
126×36001000​=126×185​=35 m/s.
Step 3: Calculate the total distance to be covered.
Length of faster train =
267 m.
Length of slower train =
153 m.
Total distance =
267+153=420 m.
Step 4: Find the time taken to overtake.
Time =
Relative speedTotal distance​=35420​=12 seconds.
Answer:The faster train will take
12 seconds to completely overtake the slower one. Thus, the correct option is D (12 seconds).