Question

Two trains running in opposite directions cross a pole in 43 seconds and 27 seconds respectively and cross each other in 37 seconds. What is the ratio of their speeds?
1. 5 : 3
2. 4 : 5
3. 6 : 1
4. 7 : 5
5. None of the above

Answer 1

Correct Answer - Option 1 : 5 : 3

Given:

Two trains running in opposite directions cross a pole in 43 seconds and 27 seconds respectively.

Time taken to cross each other = 37 sec

Concept:

Relative speed.

Calculation:

Let the speed of the trains be x and y m/s (meters per second) respectively.

∴ Length of first train = 43x and length of second train = 27y meters

Since the trains run in opposite directions, their relative speed = (x + y) m/s

∴ (43x + 27y)/(x + y) = 37

⇒ 43x + 27y = 37x + 37y

⇒ 6x = 10y

∴ Required Ratio

⇒ 10 : 6

⇒ 5 : 3

The ratio of their speeds is 5 : 3.