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    Question

    A motor boat covers a certain distance downstream in a

    river in 5 hours. It covers the same distance upstream in 5 hours and 30 minutes. If the speed of water is 2 km/h, then the speed of the boat in still water is:
    A 27 km/hr Correct Answer Incorrect Answer
    B 15 km/hr Correct Answer Incorrect Answer
    C 34 km/hr Correct Answer Incorrect Answer
    D 45 km/hr Correct Answer Incorrect Answer
    E 42 km/hr Correct Answer Incorrect Answer

    Solution

    Let the speed of boat in still water be x km/hr and the distance be y km. Rate downstream = (x + 2) km/hr Rate upstream = (x – 2) km/hr According to the question, y/(x + 2) = 5 --- (i) y/(x – 2) = 11/2 --- (ii) On dividing equation (i) by (ii), (x – 2)/(x + 2) = 5/(11/2) = 10/11 11x – 22 = 10x + 20 x = 22 + 20 = 42 kmph

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