Question

9. The value of U.S. postage stamps increases -5% per year. The current price is 55€. Estimate what the price will be in 20 years​

Answer 1

`\qquad \textit{Amount for Exponential Growth} \\\\ A=P(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{initial amount}\dotfill &\$0.55\\ r=rate\to 5\%\to (5)/(100)\dotfill &0.05\\ t=years\dotfill &20\\ \end{cases} \\\\\\ A=0.55(1 + 0.05)^(20)\implies A=0.55(1.05)^(20)\implies A\approx 1.46`