Question

    A traveler at four-fifths of his normal speed takes 20

    minutes longer than his usual time to reach his destination. What is his usual travel time?
    A 19 min Correct Answer Incorrect Answer
    B 12 min Correct Answer Incorrect Answer
    C 20 min Correct Answer Incorrect Answer
    D 25 min Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the usual speed of the traveler be '5s' km/h and the distance be 'd' km.

    Let the usual time taken be 't' hours.

    ATQ;

    (d/5s) = t

    Or, d = 5ts ........ (I)

    Traveling at four-fifths of his normal speed:

    (d/(4s)) = t + (20/60)

    Using equation (I), we have;

    (5ts/4s) = t + (1/3)

    Or, 5t = 4t + (1/3)

    Or, t = (1/3)

    Thus, the usual time taken by the traveler to reach his destination = (1/3) hours or 20 minutes.

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