A train takes 7 seconds to pass a man standing on a platform, and another train, whose length is double that of the first train, and moving in the opposite direction, takes 10 seconds to pass him. The time taken (in seconds, to the nearest integer) by the trains to pass each other will be:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 9.
Let the length of A = L
Relative speed = L/7 + 2L/10 = 12L/35
Time to pass each other = (L + 2L)/(12L/35)
= 3L × 35/12L
= 8.75 sec ≈ 9 sec