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What is the spead of train Problem

In a Tunnel 1 KM long. Two friends are standing at 600m inside the Tunnel (i.e. 600m from 1 side and 400m from other).Suddenly they heard the whistle of a train.Both started to run on opposite direction at spead of 10 KM/Hr.Both of them just survived.
What is the speed of train?

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  1. nice one following ur blog

  2. All it said was they heard the whistle of a train! There is nothing to say that the train is even moving let alone in the tunnel!
    The train was stationary! :)

  3. Train will enter from the side where the Person (A) is travelling distance 400meters. So at 10km/hr he will pass the tunnel (400m ) in 60min *0.4 m / 10 = 2.4min. Where as other person (B) has to travell 600meters with 10km/hr so he will require 60min * 0.6mters /10 = 3.6 min.

    When A exits from tunnel, train in entering in tunnel. Means in 2.4 min B has moved 400mters in other direction. Remaining 200 min he will require 1.2min. So in 1.2 min train has to travel 1km. so speed will be in 1.2 min - 1km so in 60 min = 60 * 1 /1.2 = 50Km/Hr....

    ANSWER is 50 km/Hr.

  4. yes , its 50 KM/Hr