One train is moving with at twice the speed of a second train. The lengths of the trains are equal. The ratio of the time taken by these trains to cross each other when moving in the same direction and in opposite directions, respectively, is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 3 : 1.
Let the speed of the second train = x
Then the first train's speed = 2x
Let the length of each train be L
Same direction: Relative speed = 2x - x = x
Distance = L + L = 2L
Time = 2L ÷ x
Opposite direction:
Relative speed = 2x + x = 3x
Distance = 2L
Time = 2L ÷ 3x
Ratio of times (same direction : opposite direction) = (2L ÷ x) : (2L ÷ 3x) = 1 : (1/3) = 3 : 1