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

    Question

    Speed of a boat in still water is 6 times more than the

    speed of stream. If boat covers 112 km in downstream in 8 hours, then find the time taken by the boat to cover 90 km in upstream.
    A 12 hours Correct Answer Incorrect Answer
    B 10 hours Correct Answer Incorrect Answer
    C 8 hours Correct Answer Incorrect Answer
    D 9 hours Correct Answer Incorrect Answer
    E 7 hours Correct Answer Incorrect Answer

    Solution

    Let the speed of stream be ‘x’ km/hr. So, speed of boat in still water = 6 × x = 6x km/hr Downstream speed of boat = 6x + x = 7x km/hr According to question; 7x = 112/8 = 14 Or, x = 2 Upstream speed of the boat = 6x – x = 5x = 5 × 2 = 10 km/hr Required time taken = 90/10 = 9 hours

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