Question

A train X passes another train Y whose length is 2 times more than the length of the X in opposite direction in 20 seconds. Train X passes a platform of 250 m length with a speed of 30 m/sec in 15 seconds. Find the speed of train Y in m/sec?

1. 12
2. 10
3. 15
4. 16

Answer 1

Correct Answer - Option 2 : 10

Given:

Train X passes a platform of length 250 m with a speed of 30 m/sec in 15 seconds.

Train X and Y are traveling in the opposite direction.

The length of train Y is 2 times more than the length of train X.

Formula Used:

Relative speed = Distance/Time

Calculation:

Let the length of train X be L m and then the length of train Y will be 3L m.

Length or total distance will be given by

⇒ (250 + L) = 30 × 15 = 450 m.

⇒ L = 450 – 250 = 200 m

Now train X and Y crosses each other in 20 seconds when they travel in the opposite direction.

Let the speed of train Y be S m/sec.

⇒ Length of Y = 3L

⇒ 3 × 200

⇒ 600 m

Now the relative speed of both will be,

⇒ (200 + 600 ) = (30 + S) × 20

⇒ 800 = 600 + 20S

⇒ S = 10 m/sec

∴ The speed of train Y is 10 m/sec.

• Here, Length of Train Y = 3(Length of Train X) because in the question it is mentioned that "the length of train Y is 2 times more than length of train X"
• If "the length of train Y is 2 times length of train X" then Length of Train Y = 2(Length of Train X).