Question

    The speed of a boat in still water is 8.5 times the

    speed of the stream. If the difference between the upstream and downstream speed of the boats is 22 km/hr, then find the time taken by the boat to travel 495 km in upstream.
    A 5 hours Correct Answer Incorrect Answer
    B 2 hours Correct Answer Incorrect Answer
    C 4 hours Correct Answer Incorrect Answer
    D 6 hours Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the speed of the stream be ‘x’ km/hr Therefore, speed of the boat in still water = 8.5x km/hr Upstream speed of the boat = 8.5x – x = 7.5x km/hr Downstream speed of the boat = x + 8.5x = 9.5x km/hr According to the question, 9.5x – 7.5x = 22 => 2x = 22 => x = 11 Therefore, upstream speed of the boat = 7.5x = 82.5 km/hr Required time taken = 495/82.5 = 6 hours

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