Q:

# How do you calculate population growth?

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Subtracting a past population value from the present population value, and dividing this result by the past population value, yields the population-growth rate. Multiplying the population-growth rate by 100 yields the growth percentage.

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Population growth is a change in population size during a particular time period. In the simplest calculation, growth rate is equal to [P(t2) - P(t1)]/P(t1), where P(t1) is a past population value and P(t2) is the present population. This calculation yields a growth rate for any chosen time range. It is common to express growth rate as a percentage by multiplying the rate by 100. Dividing the percent population growth by the number of years between t1 and t2 gives an annual growth percentage. For example, a population that experiences 10 percent growth in 10 years has a 1 percent annual growth rate.

The population growth calculation is also an excellent tool for predicting future populations, given a known growth rate. In this case P(t2) is a future population, and the unknown variable, and P(t1) is the present population.

Another method of predicting a future population is to find doubling time. Doubling time is the result of dividing 70 by the percent growth. In this calculation 70 is a constant that derives from the natural log of 2.

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## Related Questions

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Around 49.6 percent of the world's population is female, giving a total female population of around 3.52 billion in the world as of 2014. There are 101 men for every 100 women across the globe. At birth, men outnumber women 107 to 100, but male life span is shorter.

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There are five main characteristics of a population and these include population size, population density, population distribution, age structure and reproductive base. These characteristics of a population can be found in population ecology, which is a combination of the study of how organisms interact with each other and their environment focusing on the group of individuals of the same species, most often humans in population ecology, who live in a given area.

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Populations grow exponentially when they can maintain a constant growth rate percentage and can leverage the steady increase in population. Exponential growth of various species have been seen throughout Earth's history.