New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    The speed of a boat in still water is 50% more than the

    speed of the stream such that the boat takes 3 hours to cover 81 km downstream. If the speed of the boat in still water is reduced by 20%, then find the distance covered by the boat in 5 hours upstream.
    A 5 km Correct Answer Incorrect Answer
    B 6 km Correct Answer Incorrect Answer
    C 12 km Correct Answer Incorrect Answer
    D 18 km Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ, Let the speed of the stream be 10x km/hr. So, speed of the boat in still water = 1.5×10x=15x km/hr ATQ, Speed of stream = 10x = 10.8 km/hr Now, Reduced speed of boat in still water = 15x × 0.8 = 12 km/hr Therefore, required distance = (12−10.8)×5 = 6 km

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