Question

    A man can row at 20 km/hr in still water. If the

    velocity of current is 4 km/hr and it takes him 1 hour to row to a place and come back, how far is the place?
    A 7.2 km Correct Answer Incorrect Answer
    B 4.8 km Correct Answer Incorrect Answer
    C 9.6 km Correct Answer Incorrect Answer
    D 2.1 km Correct Answer Incorrect Answer
    E 3.75 km Correct Answer Incorrect Answer

    Solution

    Let the distance be x km. Speed upstream = 20 – 4 = 16 km/hr Speed downstream = 20 + 4 = 24 km/hr ⇒ x/16 + x/24 = 1 ⇒ (3x + 2x)/48 = 1 ⇒ 5x = 48 ⇒ x = 48/5 = 9.6 km

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