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

    Question

    A boat can travel 21 km downstream in 42 min. The ratio

    of the speed of the boat in still water to the speed of the stream is 5: 1. How much time will the boat take to cover 25 km upstream?
    A 1(5/6) hr Correct Answer Incorrect Answer
    B 3(2/3) hr Correct Answer Incorrect Answer
    C 1(1/4) hr Correct Answer Incorrect Answer
    D 2(1/7) hr Correct Answer Incorrect Answer

    Solution

    Speed of downstream = D/T = 21 × (60/42) = 30 km/hr The ratio of the speed of the boat in still water to the speed of the stream = 5: 1 (5x, x) => 6x = 30 => x = 5 Speed of upstream = 5x – x = 4x = 20 km/hr Distance = 25 km Time = D/S = 25/20 = 1(1/4) hr 

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