Question

    The speed of the boat in still water is 12 km/hr and the

    speed of the stream is 9 km/hr. A boat goes 84 km downstream with its usual speed but at the time of returning the speed of the boat in still water is doubled. Find the total time taken by boat to cover the whole distance.
    A 6.6 hours Correct Answer Incorrect Answer
    B 12 hours Correct Answer Incorrect Answer
    C 10 hours Correct Answer Incorrect Answer
    D 9.6 hours Correct Answer Incorrect Answer

    Solution

    According to the question, Required time = 84/(12 + 9) + 84/(24 – 9) => 84/21 + 84/15 => 4 + 5.6 = 9.6 hours

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