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

    Question

    The speed of a boat in still water and the speed of the

    stream are in the ratio of 5:2. If the boat's speed while moving downstream is 84 km/hr, how long will it take for the boat to cover a distance of 378 km upstream?
    A 12 hours Correct Answer Incorrect Answer
    B 8 hours Correct Answer Incorrect Answer
    C 16 hours Correct Answer Incorrect Answer
    D 10.5 hours Correct Answer Incorrect Answer

    Solution

    Let the speed of the boat in still water and the speed of the stream be '5x' km/hr and '2x' km/hr, respectively

    According to the question,

    5x + 2x = 84

    Or, 7x = 84

    Or, x = 12

    Upstream speed of the boat = 5x - 2x = 3x = 36 km/hr

    Required time taken = (378/36) = 10.5 hours

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