Question

Lisa deposited $15,000 into an account that pays a simple interest of 4%. How long will it take for his money to double?

Answer 1

`~~~~~~ \textit{Simple Interest Earned Amount} \\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\dotfill & \stackrel{ doubled }{\$ 30000}\\ P=\textit{original amount deposited}\dotfill & \$15000\\ r=rate\to 4\%\to (4)/(100)\dotfill &0.04\\ t=years \end{cases} \\\\\\ 30000 = 15000[1+(0.04)(t)] \implies \cfrac{30000}{15000}=1+0.04t\implies 2=1+0.04t \\\\\\ 1=0.04t\implies \cfrac{1}{0.04}=t\implies 25=t`