Boats and Streams


  1. A boat goes 14 km upstream in 56 minutes. The speed of stream is 2 km/hr. The speed of boat in still water is ?









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    ∵ Speed upstream = 14 x (60/56) = 15 km/hr
    Speed in upstream = Speed in still water - Speed of stream.

    Correct Option: D

    ∵ Speed upstream = 14 x (60/56) = 15 km/hr
    Speed in upstream = Speed in still water - Speed of stream.
    ⇒ x - 2 = 15
    ∴ x = 17 km/hr


  1. The speed of a boat in still water is 10 km/hr. If its speed down stream be 13 km/hr, then speed of the stream is ?









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    Speed in still water + Speed of stream = Speed in downstream.
    ⇒ 10 + y = 13

    Correct Option: B

    Speed in still water + Speed of stream = Speed in downstream.
    ⇒ 10 + y = 13
    ∴ y = 13 - 10 = 3 km/hr



  1. The speed of a boat in still water is 12 km per hour. Going downstream it moves at the rate of 19 km per hour. The speed of the boat against the stream is ?









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    Speed of stream = speed in downstream - Speed in still water
    ⇒ Speed of stream = 19 - 12 = 7 km/hr

    Speed of boat against stream = Speed in still water - Speed of stream.
    ⇒ Speed of boat against stream = 12 - 7 = 5 km/hr

    Correct Option: A

    Speed of stream = speed in downstream - Speed in still water
    ⇒ Speed of stream = 19 - 12 = 7 km/hr

    Speed of boat against stream = Speed in still water - Speed of stream.
    ⇒ Speed of boat against stream = 12 - 7 = 5 km/hr


  1. If a man rows at the rate of 5 km/hr in still water and his rate against the current is 3.5 km/hr, then the man's rate along the current is ?









  1. View Hint View Answer Discuss in Forum

    Speed of current = 5 - 3.5 = 1.5 km/hr
    Man's speed along the current = Man speed in still water + speed of current.

    Correct Option: B

    Speed of current = 5 - 3.5 = 1.5 km/hr
    Man's speed along the current = Man speed in still water + speed of current.
    ⇒ Man's speed along the current = 5 + 1.5 = 6.5 km/hr



  1. A man rows upstream 16 km and downstream 27 km talking 5 hours each time. What is the velocity of current ?









  1. View Hint View Answer Discuss in Forum

    ∵ Man's rate upstream = 16/5 km/hr
    Man's rate downstream = 27/5 km/hr

    Correct Option: C

    Man's rate upstream = 16/5 km/hr
    Man's rate downstream = 27/5 km/hr

    ∴ Velocity of the current = (27/5 - 16/5)/2 km/hr = 1.1 km/hr