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

    Question

    A boat travels upstream from B to A and downstream from

    A to B in 3 hours. If the speed of the boat in still water is 9 km/h and the speed of the current is 3.5 km/h, the distance between A and B is: (correct up to two decimal places)
    A 14.46 km Correct Answer Incorrect Answer
    B 13.46 km Correct Answer Incorrect Answer
    C 12.46 km Correct Answer Incorrect Answer
    D 11.46 km Correct Answer Incorrect Answer

    Solution

    Upstream speed = 9-3.5 = 5.5 km/hr Downstream speed = 9 + 3.5 = 12.5 km/hr   Let the distance between A and B be x km, then According to the question   x/12.5 + x/5.5 = 3 (2x/25 + 2x/11) = 3 (50x+22x)/25×11 = 3 72x/275 = 3 x = (3 × 275)/72 x = 11.46 km The distance between A and B is 11.46 km.

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