keeping in mind that a year has 12 months, thus 6 months is really 6/12 of a year.
[tex]~~~~~~ \textit{Simple Interest Earned} \\\\ I = Prt\qquad \begin{cases} I=\textit{interest earned}\\ P=\textit{original amount deposited}\dotfill & \$630\\ r=rate\to 6.5\%\to \frac{6.5}{100}\dotfill &0.065\\ t=years\to \frac{6}{12}\dotfill &\frac{1}{2} \end{cases} \\\\\\ I = (630)(0.065)(\frac{1}{2}) \implies I\approx 20.48[/tex]
