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

    Question

    A boatman rows 7 km in 10 minutes, along the stream and

    42 km in 2 hours against the stream. The speed of the stream is:
    A 10.6 km/hr Correct Answer Incorrect Answer
    B 31.5 km/hr Correct Answer Incorrect Answer
    C 16 km/hr Correct Answer Incorrect Answer
    D 32 km/hr Correct Answer Incorrect Answer
    E 21 km/hr Correct Answer Incorrect Answer

    Solution

    Rate downstream = 7/10 x 60 = 42 km/hr Rate upstream = 42/2 = 21 km/hr Speed of current = 1/2 (Rate downstream – Rate upstream) ⇒ 1/2 (42 – 21) km/hr = 10.5 km/hr

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