A train leaves London at 5 AM and another train leaves Paris an hour later .…

2024

A train leaves London at 5 AM and another train leaves Paris an hour later . If the two trains pass each other right in the middle of the journey , and the distance between London and Paris is 400 km . If the speed of the London train is 60 km/hr , then find the speed of the Paris train.

  1. A.

    90 km/hr

  2. B.

    56 km/hr

  3. C.

    75 km/hr

  4. D.

    86 km/hr

Attempted by 4 students.

Show answer & explanation

Correct answer: D

Answer: 86 km/hr (exactly 600/7 km/hr).

  1. Total distance between London and Paris is 400 km, so the midpoint is 200 km from each city.

  2. The London train (speed 60 km/hr) takes 200 ÷ 60 = 10/3 hours to reach the midpoint.

  3. The Paris train starts 1 hour later, so its travel time until meeting is 10/3 − 1 = 7/3 hours.

  4. Required speed = distance ÷ time = 200 ÷ (7/3) = 200 * (3/7) = 600/7 ≈ 85.71 km/hr, which rounds to 86 km/hr.

  5. Therefore the correct speed of the Paris train is 600/7 km/hr (≈86 km/hr).

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