Question

How much should you put in an investment paying a simple interest rate of​ 5% if you needed​ $4000 in eighteen​ mont

Answer 1

now, there are 12 months in a year, so 18 months is really 18/12 of a year, thus

`~~~~~~ \textit{Simple Interest Earned Amount} \\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\dotfill & \$4000\\ P=\textit{original amount deposited}\\ r=rate\to 5\%\to (5)/(100)\dotfill &0.05\\ t=years\to (18)/(12)\dotfill &(3)/(2) \end{cases} \\\\\\ 4000=P[1+(0.05)((3)/(2))]\implies 4000=P(1.075) \\\\\\ \cfrac{4000}{1.075}=P\implies 3720.93\approx P`