Difficulty: Easy
Correct Answer: 21 sec
Explanation:
Introduction / Context:Total distance to clear a platform equals train length + platform length. Convert speed to m/s and divide total distance by that speed to get time in seconds.
Given Data / Assumptions:
Concept / Approach:S = 110 + 240 = 350 m. Time t = S / v_mps.
Step-by-Step Solution:
v = 60 * 5/18 = 50/3 ≈ 16.6667 m/s.t = 350 / (50/3) = 350 * 3 / 50 = 21 s.Verification / Alternative check:Dimensional check yields seconds; magnitude aligns with typical moderate-speed trains.
Why Other Options Are Wrong:18, 20, 24, 16 s do not match S/v with correct conversion.
Common Pitfalls:Forgetting to add both lengths; mishandling 60 km/h to m/s conversion.
Final Answer:21 sec
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