Question

Joe deposits $30,000 for his retirement in an account with a 6% simple interest rate. How long will it take Joe to earn $21,600 in interest? 5 years 7 years 10 years 12 years

Answer 1

The answer is 12 years

Answer 2

`\bf ~~~~~~ \textit{Simple Interest Earned}\\\\ I = Prt\qquad \begin{cases} I=\textit{interest earned}\to &\$21600\\ P=\textit{original amount deposited}\to& \$30000\\ r=rate\to 6\%\to (6)/(100)\to &0.06\\ t=years \end{cases} \\\\\\ 21600=(30000)(0.06)t\implies \cfrac{21600}{(30000)(0.06)}=t\implies 12=t`