Population Growth Calculations: Exponential Growth, Rule of 70 & Doubling Time Ch. 6

How Has Human Population Changed Over Time?*

Human Population is Growing Exponentially*

Exponential Growth When a quantity increases at a fixed percentage per unit of time. Example: 2% per year

Exponential Growth Example $100 invested at 7% a year annual compound interest will double in 10 years

Exponential Growth Example Applies to populations too! If a population grows at 7%/year it will double in 10 years!

Doubling Time The time it would take for population to double if it were growing exponentially at a constant rate.

Rule of 70 A trick to estimate population doubling Doubling Time (years) = 70 % Growth Rate

Population Density

Birth or Death Rate

Population Growth Rate (r)