Question

After 7 years, Amber earned $1575 in simple interest from a cd into which he initially deposited $6000. What was the annual interest rate

Answer 1

$\bf ~~~~~~ \textit{Simple Interest Earned} \\\\ I = Prt\qquad \begin{cases} I=\textit{interest earned}\to &\ 1575\\ P=\textit{original amount deposited}\to& \ 6000\\ r=rate\to r\%\to \frac{r}{100}\\ t=years\to &7 \end{cases} \\\\\\ 1575=(6000)(r)(7)\implies \cfrac{1575}{(6000)(7)}=r\implies 0.0375=r \\\\\\ r\%=0.0375\cdot 100\implies r=\stackrel{\%}{3.75}$