Question

    The Speed of boat in still water is 20 km/hr. It covers

    (upstream) a distance of 90 km in 12 hours. The speed of the stream is
    A 16.5 km/hr Correct Answer Incorrect Answer
    B 12.5 km/hr Correct Answer Incorrect Answer
    C 10.5 km/hr Correct Answer Incorrect Answer
    D 13.5 km/hr Correct Answer Incorrect Answer

    Solution

    The speed of the Boat in still water , x = 20km/hr Let the speed of current be y km/hr Now, Upstream speed = 90/12 ∴x-y = 90/12 20 – y = 90/12 y = 20 - 90/12 y = (240-90)/12 = 150/12 = 12.5km/hr

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