Multiple choice

Two stations, Ahmedabad and Baroda, are 100 km apart. Navjeevan Express, travelling at 50 kmph, leaves Ahmedabad at 6:30 a.m. and Howrah-Ahmedabad Express, travelling at 40 kmph, leaves Baroda at 7 a.m. At 7:30 a.m, Mr. Shah, the traffic controller, discovers that both the trains are travelling on the same line. How much time is available for him to avert an accident?

  1. 15 min

  2. 20 min

  3. 25 min

  4. 30 min

  5. 35 min
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

At 7:30 a.m., the Ahmedabad train has traveled for 1 hour (50 km) and the Baroda train for 30 minutes (20 km). The distance remaining between them is 100 - 50 - 20 = 30 km. Since they move toward each other at a combined speed of 90 kmph, the time until collision is 30/90 hours, which is 1/3 hour or 20 minutes.

AI explanation

Using the basic Time, Speed and Distance formula, Navjeevan Express travels for 1 hour before 7:30 a.m., covering 50 km. At 7:00 a.m., both trains are moving towards each other from a separation of 50 km, so their relative speed is 50 plus 40, which equals 90 km/hr. The time taken to collide from 7:00 a.m. is 50 divided by 90 hours, which equals 1/3 hours or 20 minutes. Because the controller discovers the issue at 7:30 a.m., he has exactly 20 minutes available to avert the accident.

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