hard algebra problem help?

anonymousanonymous
in Science & Mathematics

I train of length 100 meters drives at a relatively slow speed. A runner starts behind the train and runs past the train to the front, and then returns the same route behind the train. The speed of the runner is 3 times the speed of the train. What distance has the train travelled in this period?

Comments

  • ranjankarranjankar

    Let the speed of train be x meters / minute

    THEN the speed of runner is 3x meters/ minute

    Time taken by runner to reach the front = 100 /2x minutes

    Time taken by runner to reach the back = 100/ 4x minutes

    Total time = 50/x + 25/x = 75/x minutes

    Distance covered by train = x * 75 /x = 75 meters ANSWER

  • sepiasepia

    A train of length 100 meters drives at a relatively slow speed.

    A runner starts behind the train and runs past the train to the front,

    and then returns the same route behind the train.

    The speed of the runner is 3 times the speed of the train.

    What distance has the train travelled in this period?

    Let x be the distance the train travelled in this period.

    The runner runs at 3 times the speed of the train.

    Speed x time = distance

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