Question

Two trains running in opposite directions cross a man standing on the platform in 54 seconds and 1.5 minutes respectively. If they cross each other in 74 seconds, what will be their ratio of speed?
1. 4 ∶ 3
2. 4 ∶ 5
3. 3 ∶ 4
4. 1 ∶ 1

Answer 1

Correct Answer - Option 2 : 4 ∶ 5

Given:

The first train crosses a man = 54 seconds

Second train crosses a man = 1.5 min = 90 seconds

The first train and second train crosses to each other = 74 seconds

Formula Used:

Distance = Speed × Time

Calculation:

Let the speed of two trains be x m/s and y m/s

According to the question, we have

The length of the first train = 54x 

The length of the second train = 90y 

Now, the trains are moving in the opposite direction

Relative speed = (x + y)

The time taken by trains to cross to each other

(54x + 90y)/(x + y) = 74

⇒ 54x + 90y = 74x + 74y

⇒ 74x - 54x = 90y - 74y

⇒ 20x = 16y

⇒ x/y = 4/5

∴ The ratio of the speed of two trains is 4 ∶ 5.