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The doubling time is the time it takes for a population to double in size/value. ... Simple doubling time formula: = / where N(t) = the number of objects at time ...
The doubling time (t d) of a population is the time required for the population to grow to twice its size. [24] We can calculate the doubling time of a geometric population using the equation: N t = λ t N 0 by exploiting our knowledge of the fact that the population (N) is twice its size (2N) after the doubling time. [20]
P 0 = P(0) is the initial population size, r = the population growth rate, which Ronald Fisher called the Malthusian parameter of population growth in The Genetical Theory of Natural Selection, [2] and Alfred J. Lotka called the intrinsic rate of increase, [3] [4] t = time. The model can also be written in the form of a differential equation:
Rank Country (or dependent territory) July 1, 2015 projection [1] % of pop. Average relative annual growth (%) [2] Average absolute annual growth [3]Estimated doubling time
The formula above can be used for more than calculating the doubling time. If one wants to know the tripling time, for example, replace the constant 2 in the numerator with 3. As another example, if one wants to know the number of periods it takes for the initial value to rise by 50%, replace the constant 2 with 1.5.
One equation used to analyze biological exponential growth uses the birth and death rates in a population. If, in a hypothetical population of size N, the birth rates (per capita) are represented as b and death rates (per capita) as d, then the increase or decrease in N during a time period t will be
The formula for the Rule of 72. The Rule of 72 can be expressed simply as: ... So, for example, use 74 if you’re calculating doubling time for 16 percent interest. How the Rule of 72 works.
Rank Country (or dependent territory) July 1, 2015 projection [1] % of pop. Average relative annual growth (%) [2] Average absolute annual growth [3]Estimated doubling time