Question

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

    speed of the stream is 6 km/hr. A man rows to a place at a distance of 63 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 11 hours Correct Answer Incorrect Answer
    D 10 hours Correct Answer Incorrect Answer
    E 14 hours Correct Answer Incorrect Answer

    Solution

    Rate downstream = (15 + 6) kmph = 21 kmph Rate upstream = (15 – 6) kmph = 9 kmph According to the question, Time = Distance/Speed Hence, Required time = 63/21 + 63/9 = 3 + 7 = 10 hours

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