# Population percent increase formula

Introduction. Population growth can be modeled by an exponential equation. Namely, it is given by the formula $P(r, t, f)=P_i(1+r)^\frac{t}{f}$ where $P{_i}$ represents the initial population, r is the rate of population growth (expressed as a decimal), t is elapsed time, and f is the period over which time population grows by a rate of r. Percentage increase/decrease calculation The percentage increase/decrease from old value (V old) to new value (V new) is equal to the old and new values difference divided by the old value times 100%: percentage increase/decrease = (V new - V old) / V old × 100% Example #1 Jun 24, 2016 · Geometrical Increase Method (GEOMETRICAL PROGRESSION METHOD) In this method the percentage increase in population from decade to decade is assumed to remain constant. Geometric mean increase is used to find out the future increment in population. Since this method gives higher values and hence should be applied for a new industrial town at the ... The formula for population growth is below: Learn about Euler's number here or here. For example, if we have a population of zebras in 1990 that had 100 individuals, we know the population is growing at a rate of 5%, and we want to know what the population is in the year 2020, we would do the following to solve: