Subject
Quantitative Aptitude
Topic
Speed & Distance
A 500 meter long train takes 20 seconds to cross a lamp post. What is the speed of the train?
A 500 meter long train takes 20 seconds to cross a lamp post. What is the speed of the train?
ক)
25 km/hখ)
90 m/secগ)
54 km/hঘ)
90 km/hExplanation
When a train of length L crosses a platform having length P then it has to travel a distance that is = L + P And when the same train crosses a pole or a Person then it has to travel a distance that is = L Because in this case we will assume that the length of the pole or person is negligible. It means the train is travelling 500 meters in 20 seconds. As we know that, Distance travelled = Speed × Time taken Hence, As we know that, 1km = 1000m 1 hour = 60 min and 1 min = 60 second Hence 1 hour = 60 × 60 = 3600 second So the speed of the train = (500/20) = 25 m/sec Therefore 25 m/sec = (25 × 18)/5 km/h = 90 km/hRelated questions
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