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Homework Help: Population Growth Equation

  1. May 11, 2015 #1
    1. The population of a certain country grows according to the formula:

    N = N0e^kt

    Where N is the number of people (in millions) after t years, N0 is the initial number of people (in millions) and k = 1/20 ln 5/4.

    Calculate the doubling time of this population. Leave your answer in terms
    of ln : Do not use a calculator.

    2. I don't understand where to start off.

    3. I have basically come to the conclusion that N = 2N0
    That is how far I have come. I know I haven't done anything as of yet. But any help would be appreciated
  2. jcsd
  3. May 11, 2015 #2


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    Well, you were given a value for k. Did you plug this value into the population equation and make any obvious simplifications?
  4. May 12, 2015 #3


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    Use N=2 and No=1.
    Take natural log of both sides of the equation.
  5. May 12, 2015 #4
    Thanks for the info, will plug in the variables and see where I end up.
  6. May 13, 2015 #5


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    Science Advisor

    To see that you get the same "doubling time" for any initial value, take [tex]N= 2N_0[/tex].
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