Question

    A man can row at 9 km/hr in still water. If the velocity

    of current is 3 km/hr and it takes him 1 hour to row to a place and come back, how far is the place?
    A 4 km Correct Answer Incorrect Answer
    B 2.25 km Correct Answer Incorrect Answer
    C 9.5 km Correct Answer Incorrect Answer
    D 4.2 km Correct Answer Incorrect Answer
    E 5.25 km Correct Answer Incorrect Answer

    Solution

    Let the distance be x km. Speed upstream = 9 – 3 = 6 km/hr Speed downstream = 9 + 3 = 12 km/hr ⇒ x/6 + x/12 = 1 ⇒ (4x + 2x)/24 = 1 ⇒ 6x = 24 ⇒ x = 24/6 = 4 km

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