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    Question

    The velocity of a vessel in calm waters is 4.5 times the

    speed of the current. If the disparity between the boat's speed when moving against the current and with the current is 24 km/hr, calculate the duration it takes for the boat to journey 336 km upstream.
    A 12 hrs Correct Answer Incorrect Answer
    B 10 hrs Correct Answer Incorrect Answer
    C 2 hrs Correct Answer Incorrect Answer
    D 8 hrs Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    ATQ, Let the speed of the stream be ‘a’ km/hr Therefore, speed of the boat in still water = ‘4.5a’ km/hr Upstream speed of the boat = 4.5a – a = ‘3.5a’ km/hr Downstream speed of the boat = a + 4.5a = ‘5.5a’ km/hr ATQ, 5.5a – 3.5a = 24 Or, 2a = 24 Or, a = 12 Therefore, upstream speed of the boat = 3.5a = 42 km/hr Required time taken = 336/42 = 8 hours

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