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Discussion

  1. The speed of boat upstream and speed of boat downstream are 7 km/h and 13 km/h, respectively. Then the speed of stream and the speed of boat in still water is ?
    1. 10 km/h and 3 km/h
    2. 15 km/h and 9 km/h
    3. 20 km/h and 6 km/h
    4. 40 km/h and 12 km/h
  1. Correct Option: A

    Rate in still water=[(1/2)(u+v)] km/h
    Rate of current=[(1/2)(u-v)] km/h
    where u= speed of boat in downstream
    v=speed of boat in upstream

    Speed of boat in still water=[(1/2)(7+13)] =10 km/h
    Speed of the stream =[(1/2)(13-7)]=3 km/h

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