$$\frac{dN}{dt} = 0.8N - 0.01N^{2}$$
At what value of N, the population exhibits maximum growth ?
The provided equation represents logistic population growth:
$\frac{dN}{dt} = 0.8N - 0.01N^{2}$
This equation describes the rate of change of population size (N) over time (t).
The standard form of the logistic growth equation is:
$\frac{dN}{dt} = rN\left(1 - \frac{N}{K}\right)$
where 'r' is the intrinsic rate of increase and 'K' is the carrying capacity.
To find 'K' from the given equation, we can factor it:
$\frac{dN}{dt} = N(0.8 - 0.01N)$
Factor out 0.8:
$\frac{dN}{dt} = 0.8N\left(1 - \frac{0.01N}{0.8}\right)$
$\frac{dN}{dt} = 0.8N\left(1 - \frac{N}{80}\right)$
By comparing this with the standard form, we identify the carrying capacity:
$K = 80$
In logistic growth, the population growth rate ($\frac{dN}{dt}$) is maximum when the population size (N) is exactly half of the carrying capacity (K).
Maximum growth occurs at:
$N = \frac{K}{2}$
Substitute the value of K:
$N = \frac{80}{2}$
$N = 40$
Therefore, the population exhibits maximum growth at N = 40.