Question

Your grandfather bought a comic book for ten cents when he was eight. If he is 88 years old now. How much would that comic book cost today?

Answer 1

well, he bought it when he was 8, so to 88, that's 80 years later, so

`~~~~~~ \textit{Continuously Compounding Interest Earned Amount} \\\\ A=Pe^(rt)\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\dotfill & \$10\\ r=rate\to 4\%\to (4)/(100)\dotfill &0.04\\ t=years\dotfill &80 \end{cases} \\\\\\ A = 10e^(0.04\cdot 80) \implies A \approx \stackrel{ cents }{245.33}\implies A\approx \$2.45`