The current human population of the earth is more than 6 billion (year 2001). Population growth without an environmentally limiting factor growing at a constant rate is described mathematically as an exponential functions.

Exponential Growth

P = Population Po = Initial Population k = growth constant t = time

A bounded population is limited. Its growth slowly approximates a terminal value or carrying capacity. This type of growth is modeled with a logistic equation.

Logistic Growth

P = Population L = Population Maximum (Carrying Capacity) A = equation constant k = growth constant t = time

Investigate modeling population growth at the University of Minnesota.