Question

    The speed of a boat in still water is 40% less than its

    speed while moving downstream. If the boat takes 8 hours to travel 160 km upstream, how long will it take to cover a distance of 320 km downstream?
    A 1.5 hrs Correct Answer Incorrect Answer
    B 13.5 hrs Correct Answer Incorrect Answer
    C 4.8 hrs Correct Answer Incorrect Answer
    D 3.2 hrs Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the downstream speed of the boat be ‘x’ km/h.

    So, the speed of the boat in still water = 0.60x km/h

    So, the speed of the stream = x – 0.60x = 0.40x km/h

    Upstream speed of the boat = 0.60x – 0.40x = 160/8

    0.20x = 20 km/h

    x = 100 km/h

    So, the time taken by the boat to cover 320 km downstream = 320/100 = 3.2 hours

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