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    Question

    Time taken by the boat to cover ‘x’ km in downstream

    is 6 hours and the time taken by the boat to cover (x – 56) km in upstream is 8 hours. The speed of the current is 1/4th of the downstream speed of the boat. Find the speed of the boat in still water.
    A 45 km/h Correct Answer Incorrect Answer
    B 84 km/h Correct Answer Incorrect Answer
    C 67 km/h Correct Answer Incorrect Answer
    D 21 km/h Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the speed of the boat in still water be B km/hr and the speed of the current be C km/hr Speed of current is 1/4th of downstream speed (B + C)/4 = C (B + C)/C = 4/1 Let, B + C = 4y C = y So, B = 4y – y = 3y km/hr B – C = 3y – y = 2y km/hr Downstream distance – upstream distance = 56 km 4y * 6 – 2y * 8 = 56 24y – 16y = 56 8y = 56 y = 7 km/hr Speed of the boat in still water = 3 * 7 = 21 km/hr

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