Question

    A boatman rows 3 km in 4 minutes, along the stream and

    18 km in 2 hours against the stream. The speed of the stream is:
    A 36 km/hr Correct Answer Incorrect Answer
    B 9 km/hr Correct Answer Incorrect Answer
    C 18 km/hr Correct Answer Incorrect Answer
    D 22.5 km/hr Correct Answer Incorrect Answer
    E 27 km/hr Correct Answer Incorrect Answer

    Solution

    Rate downstream = 3/4 x 60 = 45 km/hr Rate upstream = 18/2 = 9 km/hr Speed of current = 1/2 (Rate downstream – Rate upstream) ⇒ 1/2 (45 – 9) km/hr = 18 km/hr

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