Question

Find the annual interest rate I= 20$ P=1000 t= 4 months

Answer 1

keeping in mind that since a year is 12 months, then 4 months is really 4/12 of a year, so

`~~~~~~ \textit{Simple Interest Earned} \\\\ I = Prt\qquad \begin{cases} I=\textit{interest earned}\dotfill & \$ 20\\ P=\textit{original amount deposited}\dotfill & \$1000\\ r=rate\to r\%\to (r)/(100)\\ t=years\to (4)/(12)\dotfill &(1)/(3) \end{cases} \\\\\\ 20 = (1000)((r)/(100))((1)/(3))\implies 20=\cfrac{1000r}{300} \implies 6000=1000r \\\\\\ \cfrac{6000}{1000}=r\implies \stackrel{\%}{6}=r`