Logistic Growth Function and Differential Equations

The Organic Chemistry Tutor2 minutes read

Logistic equations explain exponential versus logistic growth, with logistic growth reaching a limit known as carrying capacity. By solving for b and k, the logistic equation predicts the population growth of dogs on an island, reaching approximately 1,094 dogs by 2020.

Insights

  • Logistic equations differentiate between exponential and logistic growth, with exponential growth being unrestricted and logistic growth having a limit called carrying capacity.
  • Deriving the logistic curve equation involves manipulating the differential equation through partial fractions and integration, providing a mathematical framework to model population growth with resource constraints.

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Recent questions

  • What is logistic growth?

    Logistic growth has a limit called carrying capacity.

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Summary

00:00

Logistic Equations: Exponential vs. Logistic Growth

  • Logistic equations focus on exponential vs. logistic growth, with exponential growth being unlimited and logistic growth having a limit known as the carrying capacity.
  • Logistic curves describe population growth, where resources limit growth to a certain point.
  • Differential equations for exponential growth: dy/dt = ky, and for logistic growth: dy/dt = ky(1 - y/l).
  • Exponential growth increases proportionally to population size, while logistic growth behaves exponentially at low populations and levels off at the carrying capacity.
  • General solution for exponential growth: y = ce^(kt), and for logistic growth: y = l/(1 + be^(-kt)).
  • Deriving the logistic curve equation involves manipulating the differential equation through partial fractions and integration.
  • The process involves setting up partial fractions, solving for constants a and b, integrating, and simplifying to derive the general logistic equation.
  • Applying the derived logistic equation to a problem involving the release of dogs on an island in 2005 and calculating the population in 2012.

21:24

"Island Dog Population Growth Analysis"

  • The island can sustain a maximum of 5,000 dogs assuming logistic growth.
  • The general equation for the population at any time is y = L / (1 + b * e^(-kt)).
  • In 2005, the population started with 100 dogs (p(0) = 100).
  • By 2012 (t = 7), the population had grown to 324 dogs (p(7) = 324).
  • The carrying capacity (L) is 5,000 dogs, and the goal is to solve for b and k.
  • Solving for b: b = 49.
  • Solving for k: k = 0.1746.
  • The population equation is p(t) = 5000 / (1 + 49 * e^(-0.1746t)).
  • By 2020 (t = 15), there will be approximately 1,094 dogs on the island.
  • The population will reach 1,000 dogs between 2019 and 2020.
  • Approximately 94 dogs are born per year in 2016.
  • To estimate population growth, the average rate of change between 2012 and 2020 is used.
  • By calculating the population in 2015 and 2017, the average growth rate in 2016 is found to be around 93.85.
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