A 240 m long train crosses a platform of equal length (240 m) in 27 seconds. What is the train’s speed in km/h?
Aptitude
Problems on Trains
Difficulty: Easy
Choose an option
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A48
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B60
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C56
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D64
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E52
Answer
Correct Answer: 64
Explanation
Introduction / Context:Total distance to cross equals the sum of train and platform lengths. With time in seconds, find m/s then convert to km/h.
Given Data / Assumptions:
- L_train = 240 m; L_platform = 240 m; total S = 480 m.
- t = 27 s.
Concept / Approach:v_mps = S/t = 480/27 = 160/9 ≈ 17.7778 m/s; v_kmph = v_mps * 3.6 ≈ 64 km/h.
Step-by-Step Solution:
v_mps = 480/27 ≈ 17.7778.v_kmph = 17.7778 * 3.6 ≈ 64.Verification / Alternative check:Back convert: 64 km/h = 17.7778 m/s; over 27 s gives 480 m—correct.
Why Other Options Are Wrong:48, 52, 56, 60 km/h correspond to arithmetic mean errors or rounding the time improperly.
Common Pitfalls:Using only train length; mixing hours/minutes/seconds in conversion.
Final Answer:64