Question

    A man rows a boat 60 kms in 4 hours downstream and

    returns upstream in 12 hours. The speed of the stream (in km per hour) is:
    A 15 km/hr Correct Answer Incorrect Answer
    B 5 km/hr Correct Answer Incorrect Answer
    C 10 km/hr Correct Answer Incorrect Answer
    D 20 km/hr Correct Answer Incorrect Answer
    E 7.5 km/hr Correct Answer Incorrect Answer

    Solution

    Rate downstream = 60/4 = 15 km/hr Rate upstream = 60/12 = 5 km/hr Now, speed of the stream = (rate downstream – rate upstream)/2 ⇒ (15 – 5)/2 = 5 km/hr

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