A train takes 25 seconds to pass a pole and 73 seconds to pass a platform of 480 m length. What is the length of the train (in meters)?

Appeared in: JSSH Staff Nurse - 2019

Explanation

The core principle is that the extra time taken to cross the platform versus the pole is the exact time needed to cover the length of the platform.
First, calculate the time difference: 73 seconds (platform) - 25 seconds (pole) = 48 seconds. This is the time taken to travel the 480m length of the platform.
Next, calculate the train's speed: Speed = Distance / Time = 480 m / 48 s = 10 m/s.
Finally, calculate the train's length. The train takes 25 seconds to pass a pole, which means it covers its own length in that time.
Length = Speed × Time = 10 m/s × 25 s = 250 meters.

Option B: This would imply a speed of 9.6 m/s (240m / 25s), which is inconsistent with the time taken to cross the platform.
Option C: This is a result of incorrect calculation and does not align with the speed derived from the problem's data.
Option D: This would imply a speed of 10.8 m/s (270m / 25s). At this speed, the train would cross the 480m platform in approximately 44.4 seconds, not 48 seconds.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculating speed, distance, and time in the context of a train crossing objects of negligible length (pole) and significant length (platform) as background academic context rather than a clinical decision trigger.
This type of question tests logical reasoning and the ability to apply mathematical formulas, a skill useful in various analytical tasks required in both academic and professional settings.
Understanding the relationship between speed, distance, and time is a fundamental concept in physics and a common component of general aptitude tests.
This problem-solving approach—breaking down a complex problem into simpler parts—is a valuable skill in many fields, including healthcare, for tasks like calculating drug dosages or infusion rates.

How to Approach the Question

First, identify the knowns: time to pass a pole (25s), time to pass a platform (73s), and platform length (480m).
Recognize that the distance covered when crossing a pole is the train's own length (L).
Recognize that the distance covered when crossing a platform is the train's length plus the platform's length (L + 480m).
Calculate the difference in time (73s - 25s = 48s). This is the time taken to cover the extra distance, which is the length of the platform.
Use this information to find the train's speed: Speed = Distance / Time = 480m / 48s = 10 m/s.
Finally, calculate the train's length using the time it takes to pass the pole: Length = Speed × Time = 10 m/s × 25s.

Concept Tested & Keywords

Concept Tested: Calculating speed, distance, and time in the context of a train crossing objects of negligible length (pole) and significant length (platform).
Stem keywords: train, pass a pole, pass a platform, length of the train
Lead-in keywords: What is the length

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Practise the full JSSH Staff Nurse - 2019

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