Question

    A man rows a boat 45 kms in 4 hours downstream and

    returns upstream in 12 hours. The speed of the stream (in km per hour) is:
    A 3.75 km/hr Correct Answer Incorrect Answer
    B 11.25 km/hr Correct Answer Incorrect Answer
    C 8 km/hr Correct Answer Incorrect Answer
    D 6 km/hr Correct Answer Incorrect Answer
    E 2 km/hr Correct Answer Incorrect Answer

    Solution

    Rate downstream = 45/4 = 11.25 km/hr Rate upstream = 45/12 = 3.75 km/hr Now, speed of the stream = (rate downstream – rate upstream)/2 ⇒ (11.25 – 3.75)/2 = 3.75 km/hr

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