Results 1 to 8 of 8

Math Help - stupid test question.

  1. #1
    Junior Member autumn's Avatar
    Joined
    Mar 2010
    From
    unfortunalty, im stuck in hicks state. IN.
    Posts
    41

    stupid test question.

    i DO understand how to do this, i just cant remember how to get all of the numbers in the equation in order to solve it.
    "The population of a town is 10000 people. it grows at a rate of 1.4% per year for four years, what is the growth factor, b, for the equation y=a*bx (x being the small integer over the b)"

    i get that a = 10000
    i get that b = 1.4
    i get that x = 4
    but none of the answers i come out with is in the multiple choice.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,829
    Thanks
    123
    Quote Originally Posted by autumn View Post
    i DO understand how to do this, i just cant remember how to get all of the numbers in the equation in order to solve it.
    "The population of a town is 10000 people. it grows at a rate of 1.4% per year for four years, what is the growth factor, b, for the equation y=a*bx (x being the small integer over the b)"

    i get that a = 10000
    i get that b = 1.4 <<<<<<<< where did you get this number from?
    i get that x = 4
    but none of the answers i come out with is in the multiple choice.
    1. If x = 1 then the population is:

    p = 10000 + \frac{1.4}{100} \cdot 10000 = 10140

    2. Plug in these values and calculate the value of b.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,707
    Thanks
    626
    Hello, autumn!

    Your explanation could be clearer . . .


    The population of a town is 10,000 people.
    It grows at a rate of 1.4% per year for four years.
    Find the growth factor b for the equation: . y\:=\:a\cdot b^x

    When x = 0,\;y = 10,\!000

    We have: . 10,\!000 \:=\:a\cdot b^0  \quad\Rightarrow\quad a \,=\,10,\!000

    . . The function is: . y \:=\:10,\!000\cdot b^x



    A little baby-talk:

    After one year (t = 1), the population increased by 1.4%.
    . . The increase is: . 0.014 \times 10,\!000 \,=\,140
    Hence, the new population is: 10,\!140

    We have: . 10,\!140 \:=\:10,\!000\cdot b^1 \quad\Rightarrow\quad b \:=\:\frac{10,\!140}{10,\!000}


    Therefore, the growth factor is: . \boxed{b \:=\:1.014}

    . . The population function is: . y \;=\;10,\!000\cdot 1.014^x

    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member autumn's Avatar
    Joined
    Mar 2010
    From
    unfortunalty, im stuck in hicks state. IN.
    Posts
    41

    Red face hmmm. thanks.

    thank you. these answers will realy help me in the long run if i just sit and mess with that formula.
    i feel stupid asking such a simple question though.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member autumn's Avatar
    Joined
    Mar 2010
    From
    unfortunalty, im stuck in hicks state. IN.
    Posts
    41

    explination

    i got the 1.4 because it is the population growth rate. population times growth rate to the power of the number of years. am i wrong?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Super Member
    Joined
    Nov 2007
    From
    Trumbull Ct
    Posts
    909
    Thanks
    27
    Quote Originally Posted by autumn View Post
    i DO understand how to do this, i just cant remember how to get all of the numbers in the equation in order to solve it.
    "The population of a town is 10000 people. it grows at a rate of 1.4% per year for four years, what is the growth factor, b, for the equation y=a*bx (x being the small integer over the b)"

    i get that a = 10000
    i get that b = 1.4
    i get that x = 4
    but none of the answers i come out with is in the multiple choice.

    Hi Autuum,

    So what did you get for the growth factor.Did you divide the % increase by 100? How many people will there be after one year? Can you see how to expand for 4 years?


    bjh
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,541
    Thanks
    1394
    Quote Originally Posted by autumn View Post
    i got the 1.4 because it is the population growth rate. population times growth rate to the power of the number of years. am i wrong?
    You got 1.4 for what? The rate of change was given as 1.4% or 0.014 so the population will increase by 0.14 of the original amount. Added to the original amount, the population will be 1.014 of the original amount which means that in one year the population is multiplied by 1.014. That, as Soroban told you, is b.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Junior Member autumn's Avatar
    Joined
    Mar 2010
    From
    unfortunalty, im stuck in hicks state. IN.
    Posts
    41

    i get it now

    at first i couldnt remember to divide the percentage (or 0.14) by the original number. i knew i was missing a step, but i couldnt find it. but now it makes a lot of sence. im dont have an algabra teacher. im on my own in this subject, hence my ignorence. your help is appreceated.
    (also... please disregard my spelling. or lack there of)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. stupid normal distribution question
    Posted in the Advanced Statistics Forum
    Replies: 4
    Last Post: February 24th 2010, 03:03 PM
  2. Probably a stupid question...
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: February 18th 2010, 11:38 AM
  3. stupid question about
    Posted in the Algebra Forum
    Replies: 3
    Last Post: August 18th 2009, 10:03 AM
  4. Very stupid continuity question
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: April 21st 2009, 10:39 PM
  5. This may be a stupid question, but...
    Posted in the Algebra Forum
    Replies: 2
    Last Post: December 18th 2008, 11:35 AM

Search Tags


/mathhelpforum @mathhelpforum