Question

Find the annual interest rate. I=$54, P=$900, t=18 months

Answer 1

4%

Explanation:

yw

Answer 2

well, there are 12 months in a year, so 18 months will then be 18/12 of a year


`\bf ~~~~~~ \textit{Simple Interest Earned}\\\\ I = Prt\qquad \begin{cases} I=\textit{interest earned}\to &\$54\\ P=\textit{original amount deposited}\to& \$900\\ r=rate\to r\%\to (r)/(100)\\ t=years\to (18)/(12)\to &(3)/(2) \end{cases} \\\\\\ 54=(900)(r)\left( (3)/(2) \right)\implies \cfrac{54}{(900)\left( (3)/(2) \right)}=r\implies \cfrac{1}{25}=r\implies 0.04=r \\\\\\ r\%=0.04\cdot 100\implies r=\stackrel{\%}{4}`