Question

What is the length of a running train crossing another 180 metre long train running in the opposite direction?
Statement I - The relative speed of the two trains was 150 kmph. 
Statement II - The trains took 9 seconds to cross each other.

• A. If the question can be answered with the help of statement I alone.
• B. If the question can be answered with the help of statement II alone.
• C. If both, statement I and statement II are needed to answer the question.
• D. If the question cannot be answered even with the help of both the statements.

Hint:

In train problems, always combine speed and time to calculate the total distance covered, and use that to find the required values.

Answer 1

The Correct Option is C

From Statement I: The relative speed of the two trains is 150 km/h.
This gives us an idea of how fast they are moving towards each other, but we still don’t know the length of the first train.
From Statement II:The two trains took 9 seconds to cross each other, but without knowing the relative speed, we cannot determine the length of the first train.
Combining both statements:
From Statement I, we have the relative speed, and from Statement II, we know the time they took to cross each other.
Using the formula \( {Distance} = {Speed} \times {Time} \), we can calculate the total distance crossed by both trains, and then subtract the length of the second train (180 meters) to find the length of the first train.
Thus, both statements are needed to calculate the length of the train.