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Homework Help: Trying to predict US population

  1. Mar 4, 2009 #1
    1. The problem statement, all variables and given/known data
    I'm given a table of census data for the US. I'm supposed to construct a logistic population model using these numbers: (t in decades and population in millions) P(0) = 3.929, P(6) = 23.192, and P(12) = 91.972

    2. Relevant equations
    dP = P(a - bP)

    P(t) = aP0/(bP0 + (a - bP0)e-at)

    3. The attempt at a solution
    I've been working on it for several hours now. I tried to make a system of equations but the ex factor is fowling it up. I used http://www.ugrad.math.ubc.ca/coursedoc/math101/notes/moreApps/logistic.html" model but it didn't give very accurate numbers. I have 3 pages of marked out numbers and no good answers to show for it. How do I find the constants a and b?
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
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