Question

Edward invested $1600 in a savings account for 8 years. At the end of 8 years, his savings account had $1920 in it.

Answer 1

$\bf \qquad \textit{Simple Interest Earned Amount}\\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\to &\ 1920\\ P=\textit{original amount deposited}\to& \ 1600\\ r=rate\to r\%\to \frac{r}{100}\\ t=years\to &8 \end{cases} \\\\\\ 1920=1600(1+r8)\implies \cfrac{1920}{1600}=1+8r\implies \cfrac{6}{5}=1+8r \\\\\\ \cfrac{6}{5}-1=8r\implies \cfrac{\frac{6}{5}-1}{8}=r\implies \cfrac{\frac{1}{5}}{8}=r\implies \cfrac{1}{40}=r \\\\\\ 0.025=r\implies r\%=100\cdot 0.025\implies r=\stackrel{\%}{2.5}$