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

    Question

    A motorboat in still water travels at a speed of 39

    km/hr. It goes 35 km upstream in 1 hour 15 minutes. The time taken by it to cover the same distance down the stream will be :
    A 45 minutes Correct Answer Incorrect Answer
    B 42 minutes Correct Answer Incorrect Answer
    C 1 hour 21 minutes Correct Answer Incorrect Answer
    D 1 hour 15 minutes Correct Answer Incorrect Answer
    E 1 hour 36 minutes Correct Answer Incorrect Answer

    Solution

    Speed of the motorboat upstream = 35/(5/4) = 28 km/hr Let the speed of the current be x km/hr ⇒ 39 – x = 28 ⇒ x = 11 km/hr Speed of motor boat downstream = 39 + 11 = 50 km/hr Time taken to cover 35 km at 50 km/hr = 35/50 = 7/10 hours or 42 minutes

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