Question

    The speed of a boat in still water is 9 km/hr and the

    speed of the stream is 3 km/hr. A man rows to a place at a distance of 36 km and comes back to the starting point. The total time taken by him is:
    A 8 hours Correct Answer Incorrect Answer
    B 13 hours Correct Answer Incorrect Answer
    C 9 hours Correct Answer Incorrect Answer
    D 10 hours Correct Answer Incorrect Answer
    E 14 hours Correct Answer Incorrect Answer

    Solution

    Rate downstream = (9 + 3) kmph = 12 kmph Rate upstream = (9 – 3) kmph = 6 kmph According to the question, Time = Distance/Speed Hence, Required time = 36/12 + 36/6 = 3 + 6 = 9 hours

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