Question

The world population in 1975 wasapproximately 4 billion, and wasdetermined to be growingexponentially at a rate of 1.9% peryear. If the formula for populationgrowth is given as ,calculate the world populationexpected in 2015.

Answer 1

Solution

Given that

At 1975 (t = 0) The population is 4 billion

Growing exponentially, the population at any time t is

$\begin{gathered} P(n)=P(0)(1+r)^n \\ \\ \text{ where r is the rate} \\ \\ n\text{ is the number of years} \end{gathered}$

At 2015 (n = 40)

$P(40)=4(1+\frac{1.9}{100})^{40}=8.49\text{ billion}$