Multiple choice

A metro train of 120 m length is running on a bridge at a speed of 40 km/hr. The train crosses the bridge in 20 seconds. What is the length of the bridge?

  1. 102.2 m

  2. 60 m

  3. 52.2 m

  4. 50 m

  5. 56 m
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A Correct answer
Explanation

Speed = 40 km/hr = 40 * (5/18) m/s = 100/9 m/s. Distance covered in 20s = (100/9) * 20 = 2000/9 = 222.22 m. Since distance = train length + bridge length, bridge length = 222.22 - 120 = 102.22 m.

AI explanation

Using the formula for converting km/hr to m/s, we multiply 40 by 5/18 to get a speed of 100/9 m/s. The total distance covered in 20 seconds is speed multiplied by time, which is (100/9) times 20, equaling 2000/9 meters or approximately 222.2 meters. Because the total distance equals the length of the train plus the length of the bridge, we subtract the train length of 120 meters from 222.2 meters to get 102.2 meters. The result is 102.2 m.

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