Given
Population of the world in 1987 = 5 billion
Annual growth rate = 1.3% per year
Required: The projected population in 2020
The exponential population growth formula is defined as:
[tex]\begin{gathered} P\text{ = P}_0e^{rt} \\ Where\text{ P}_0\text{ is the initial population} \\ r\text{ is the \% growth rate} \\ and\text{ t is the time in years} \end{gathered}[/tex]Substituting the given values:
[tex]P(t)\text{ = 5000000000e}^{0.013t}[/tex]After 2020, t = 33 years
Hence, the population after 33 years is:
[tex]\begin{gathered} P(t=13)\text{ = 5000000000 }\times\text{ e}^{0.013\times33} \\ =\text{ 7678605171.987} \\ =\text{ 7678605172.0} \end{gathered}[/tex]Hence, the estimated population of the world in 2020 is 7678605172.0
