Question

A certain population grows exponentially. The population grows from 3500 people to 6425 people in 8 years. What is the growth rate of the population?

Answer 1

`\qquad \textit{Amount for Exponential Growth} \\\\ A=P(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\dotfill & \$6425\\ P=\textit{initial amount}\dotfill &3500\\ r=rate\to r\%\to (r)/(100)\\ t=years\dotfill &8\\ \end{cases}`

`6425=3500(1 + (r)/(100))^(8) \implies \cfrac{6425}{3500}=\left( \cfrac{100+r}{100} \right)^8\implies \cfrac{257}{140}=\left( \cfrac{100+r}{100} \right)^8 \\\\\\ \sqrt[8]{\cfrac{257}{140}}=\cfrac{100+r}{100}\implies 100\sqrt[8]{\cfrac{257}{140}}=100+r \\\\\\ 100\sqrt[8]{\cfrac{257}{140}}-100=r\implies {\LARGE \begin{array}{llll} \stackrel{\%}{7.89}\approx r \end{array}}`