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

    Question

    The speed of the boat in still water is 40% less than

    the speed of the boat in downstream. The time taken by the boat to cover 468 km distance in upstream is (t+0.5) hours. If the speed of stream is 16 km/h, then find out the value of ‘t’.
    A 50 Correct Answer Incorrect Answer
    B 54 Correct Answer Incorrect Answer
    C 62 Correct Answer Incorrect Answer
    D 58 Correct Answer Incorrect Answer
    E None of the above Correct Answer Incorrect Answer

    Solution

    Let’s assume the speed of boat in still water and the speed of stream are ‘B’ and ‘C’ respectively. The speed of the boat in still water is 40% less than the speed of the boat in downstream. B = (100-40)% of (B+C) B = 60% of (B+C) B = 0.6(B+C) If the speed of stream is 16 km/h. B = 0.6(B+16) B = 0.6B+96 B-0.6B = 9.6 0.4B = 9.6 B = 24 km/h The time taken by the boat to cover 468 km distance in upstream is (t+0.5) hours. 468/(t+0.5) = (B-C) Put the value of ‘B’ and ‘C’ in the above equation. 468/(t+0.5) = (24-16) 468/(t+0.5) = 8 468/8 = (t+0.5) (t+0.5) = 58.5 t = 58.5-0.5 Value of ‘t’ = 58

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