Respuesta :
[tex]\bf \qquad \textit{Compound Interest Earned Amount}
\\\\
A=P\left(1+\frac{r}{n}\right)^{nt}
\quad
\begin{cases}
A=\textit{accumulated amount}\\
P=\textit{original amount deposited}\to &\$9000\\
r=rate\to 7.1\%\to \frac{7.1}{100}\to &0.071\\
n=
\begin{array}{llll}
\textit{times it compounds per year}\\
\textit{quarterly, means}
\end{array}\to &4\\
t=years\to &18
\end{cases}
\\\\\\
A=9000\left(1+\frac{0.071}{4}\right)^{4\cdot 18}[/tex]