Multiple choice

A train 800 meters long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute , then the length of the tunnel (in metres) is :

  1. $130$
  2. $360$
  3. $500$
  4. $540$
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C Correct answer
Explanation

The train speed is 78 km/hr, which equals 78 * (5/18) = 65/3 m/s. In 1 minute (60 seconds), the train covers a total distance of (65/3) * 60 = 1300 meters. Since the train is 800 meters long, the tunnel length is 1300 - 800 = 500 meters.

AI explanation

Using the formula for distance covered when crossing a tunnel, multiply the speed of 78 km/hr by 5/18 to get 65/3 m/s. The total distance traveled in 60 seconds is 65/3 times 60, which is 1300 meters. Since the total distance equals the train length plus the tunnel length, subtract 800 from 1300 to find the tunnel length of 500 meters.

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