Step 1: Understand the concept of logistic growth. Logistic growth describes how a population grows when resources are limited. Unlike exponential growth, which assumes unlimited resources, logistic growth incorporates a carrying capacity (K), which is the maximum population size that the environment can sustain.
Step 2: Analyze the components of the logistic growth equation. The equation \(rac{dN}{dt} = rN ig(1 - rac{N}{K}ig)\) includes: (1) 'r', the intrinsic growth rate of the population, (2) 'N', the current population size, and (3) 'K', the carrying capacity. The term \(ig(1 - rac{N}{K}ig)\) represents the fraction of resources still available as the population approaches the carrying capacity.
Step 3: Compare the given equations. The first equation, \(rac{dN}{dt} = rN\), represents exponential growth, which does not account for resource limitations. The second equation, \(rac{dN}{dt} = rK ig(1 - rac{N}{r}ig)\), incorrectly mixes variables and does not align with the logistic growth model. The third equation, \(rac{dN}{dt} = rN ig(1 - rac{N}{K}ig)\), correctly represents logistic growth. The fourth equation, \(rac{dN}{dt} = K - N\), does not describe population growth dynamics.
Step 4: Focus on the correct equation, \(rac{dN}{dt} = rN ig(1 - rac{N}{K}ig)\). This equation shows that as the population size (N) approaches the carrying capacity (K), the growth rate slows down due to limited resources. When N is much smaller than K, the term \(ig(1 - rac{N}{K}ig)\) is close to 1, and the population grows nearly exponentially. As N gets closer to K, the term \(ig(1 - rac{N}{K}ig)\) approaches 0, slowing growth.
Step 5: Apply this understanding to real-world scenarios. Logistic growth is commonly observed in populations where resources such as food, space, or water are limited. It is a foundational concept in ecology and helps explain population dynamics in various environments.