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    Question

    The speed of a boat in still water is 15 km/hr. If the

    boat covers 120 km in upstream in 12 hours, then find the time taken by the boat to travel 120 km in downstream.
    A 7 hours Correct Answer Incorrect Answer
    B 8 hours Correct Answer Incorrect Answer
    C 6 hours Correct Answer Incorrect Answer
    D 9 hours Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the speed of the boat in still water and the speed of the current be ‘x’ km/hr and ‘y’ km/hr, respectively Upstream speed of the boat = (x – y) = 120/12 = 10 km/hr Or, 15 – y = 10 Or, y = 15 – 10 = 5 km/hr Therefore, downstream speed of the boat = 15 + 5 = 20 km/hr Required time taken = 120/20 = 6 hours

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