Question

What is interest earned on 3500 invested at 6% compounded quarterly or 12 years

Answer 1

$\bf \qquad \textit{Compound Interest Earned Amount} \\\\ A=P\left(1+\frac{r}{n}\right)^{nt} \quad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\to &\ 3500\\ r=rate\to 6\%\to \frac{6}{100}\to &0.06\\ n= \begin{array}{llll} \textit{times it compounds per year}\\ \textit{quarterly, thus four} \end{array}\to &4\\ t=years\to &12 \end{cases} \\\\\\ A=3500\left(1+\frac{0.06}{4}\right)^{4\cdot 12}\implies A=3500(1.015)^{48}$

so, the interest earned then will be  A - 3500.