Question

    A boatman rows 8 km in 12 minutes, along the stream and

    36 km in 3 hours against the stream. The speed of the stream is:
    A 26 km/hr Correct Answer Incorrect Answer
    B 7 km/hr Correct Answer Incorrect Answer
    C 20 km/hr Correct Answer Incorrect Answer
    D 10 km/hr Correct Answer Incorrect Answer
    E 14 km/hr Correct Answer Incorrect Answer

    Solution

    Rate downstream = 8/12 x 60 = 40 km/hr Rate upstream = 36/3 = 12 km/hr Speed of current = 1/2 (Rate downstream – Rate upstream) ⇒ 1/2 (40 – 12) km/hr = 14 km/hr

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