Results 1 to 2 of 2

Math Help - distance-speed problem

  1. #1
    Newbie
    Joined
    May 2008
    Posts
    12

    distance-speed problem

    Water in the murray flows at 4km/hr. If a boat takes 3 hours to complete 32km round trip (16 km downstream and 16km back upstream), what is the boat's relative speed to the water?
    so far i have found that when going upstream, the equation is (x + 4) and when going dfownstream the equation is (x-4) x being the speed of the boat. and the boats speed is 32/3
    but i am unsure how to turn this into an algebratic equation.

    thanks for your help

    Zac
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,547
    Thanks
    539
    Hello, Zac!

    You know: . \text{Distance} \:=\:\text{Speed} \times \text{Time} \quad\Rightarrow\quad T \:=\:\frac{D}{S}


    Water in the murray flows at 4 km/hr.
    If a boat takes 3 hours to complete 32 km round trip,
    what is the boat's relative speed to the water?

    so far i have found that when going upstream, the equation is (x + 4)
    and when going downstream the equation is (x - 4) . . . . These are reversed

    Let x = boat's speed.

    Going upstream, its speed is smaller: . x-4
    Going downstream, its speed is greater: . x + 4

    It went upstream 16 km at x-4 km/hr.
    . . This took: . \frac{16}{x-4} hours.

    It went downstream 16 km at x+4 km/hr.
    . . This took: . \frac{16}{x+4} hours.

    The total trip took 3 hours: . \frac{16}{x-4} + \frac{16}{x+4} \:=\:3\quad\hdots There!

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Distance, speed and time problem
    Posted in the Algebra Forum
    Replies: 4
    Last Post: December 21st 2009, 05:13 AM
  2. Speed, distance and time problem
    Posted in the Math Topics Forum
    Replies: 5
    Last Post: November 15th 2009, 08:47 AM
  3. distance/speed worded problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 21st 2009, 05:26 AM
  4. speed distance problem
    Posted in the Algebra Forum
    Replies: 1
    Last Post: May 19th 2008, 08:16 PM
  5. distance speed problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 4th 2008, 10:02 AM

Search Tags


/mathhelpforum @mathhelpforum