Question

    The ratio of the speed of the stream to the speed of the

    boat in still water is 3:7. If a distance of 280 km is covered downstream in 4 hours, determine the time required to cover the same distance upstream.
    A 10 hours Correct Answer Incorrect Answer
    B 8 hours Correct Answer Incorrect Answer
    C 9 hours Correct Answer Incorrect Answer
    D 11 hours Correct Answer Incorrect Answer
    E 12 hours Correct Answer Incorrect Answer

    Solution

    Let the speed of stream and speed of boat in still water be 3x and 7x. When it travels downstream  Then 3x+7x = 280/4 10x = 70 X = 7 time taken to cover same distance by upstream = 280/(7x-3x) = 280/28 = 10 hours

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