# Logistic function application | First order differential equations | Khan Academy | Summary and Q&A

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July 25, 2014
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Logistic function application | First order differential equations | Khan Academy

## TL;DR

The logistic differential equation provides a model for population growth that considers environmental constraints, and with advancements in technology, the Malthusian limit on population growth may be pushed higher than previously thought.

## Questions & Answers

### Q: How is the logistic differential equation used to model population growth?

The logistic differential equation considers the growth rate (r), maximum population limit (K), and initial population (N naught) to describe how a population changes over time. It provides a nonconstant solution that accounts for environmental constraints.

### Q: What assumptions are made in the given example of population growth on an island?

The assumptions in this example include an initial population of 100, a maximum population limit of 1000, and a growth rate of 2.05% per year over a 20-year period. These assumptions are used to calculate the population growth using the logistic function.

### Q: How does the plot of the logistic function demonstrate population growth on the island?

The plot shows that the population initially grows rapidly, increasing by approximately 50% in the first 20 years. However, as the population approaches the maximum limit, the growth rate slows down, indicating that the environment is constraining further growth.

### Q: How does the logistic differential equation relate to the Malthusian limit?

The logistic differential equation considers the Malthusian limit, which represents the maximum population an environment can sustain. With advancements in technology, such as improved agriculture and water management, the Malthusian limit is being pushed higher, allowing for higher population growth than previously predicted.

## Summary & Key Takeaways

• The logistic differential equation is used to model population growth, considering the maximum population limit (K), the growth rate (r), and the initial population (N naught).

• Applying the logistic function to an example of an island with an initial population of 100 and a maximum population limit of 1000, the population growth is calculated over a 20-year period.

• The growth rate (r) is determined to be 0.0205, meaning the population will increase by approximately 2.05% per year.

• The plot of the logistic function shows that the population initially grows rapidly but eventually approaches the maximum population limit, never reaching it completely.