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

    Question

    A boat covers 150 km downstream in the same time it

    takes to cover 90 km upstream. If the speed of the stream is 5 km/h, determine the speed of the boat in still water.
    A 15 Correct Answer Incorrect Answer
    B 25 Correct Answer Incorrect Answer
    C 20 Correct Answer Incorrect Answer
    D 32 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the speed of boat in still water be 'v' km/h.

    So, 150 ÷ (v + 5) = 90 ÷ (v - 5)

    Or, 15 × (v - 5) = 9 × (v + 5)

    Or, 15v - 75 = 9v + 45

    Or, 6v = 120

    So, v = 20

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