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

    Question

    A boat can travel 30 km downstream in 45 min. The ratio

    of the speed of the boat in still water to the speed of the stream is 5: 3. How much time will the boat take to cover 25 km upstream?
    A 1-hour 45 min Correct Answer Incorrect Answer
    B 2-hour 45 min Correct Answer Incorrect Answer
    C 2-hour 30 min Correct Answer Incorrect Answer
    D 2 hours Correct Answer Incorrect Answer
    E 1 hour 30 min Correct Answer Incorrect Answer

    Solution

    Speed of downstream = D/T = 30 × (60/45) = 40 km/hr The ratio of the speed of the boat in still water to the speed of the stream = 5: 3 (5x, 3x) => 8x = 40 => x = 5 Speed of upstream = 5x – 3x = 2x = 10 km/hr Distance = 25 km Time = D/S = 25/10 = 2(1/2) hr = 2-hour 30 min

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