A train 150 meters long takes 20 seconds to cross a platform 250 meters long.
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A train 150 meters long takes 20 seconds to cross a platform 250 meters long. What is the speed of the train in km/hr?
Show answer & explanation
To find the speed of the train, the total distance covered (length of train + length of platform) is divided by the time taken. The resulting speed in m/s is then converted to km/hr by multiplying by 18/5.
Step-by-step Derivation:
Step 1: Calculate the total distance covered by the train to cross the platform. Total Distance = Length of Train + Length of Platform = 150 m + 250 m = 400 meters.
Step 2: Calculate the speed of the train in meters per second (m/s) using the formula Speed = Distance / Time. Speed = 400 m / 20 s = 20 m/s.
Step 3: Convert the speed from m/s to km/hr. Since 1 m/s = 3.6 km/hr (or 18/5 km/hr), Speed = 20 * (18/5) = 4 * 18 = 72 km/hr.