3. Using the following frequency distribution of marks of students of a school, find range and relers range of the marks.
\begin{tabular}{|l|c|c|c|c|c|c|}
\hline Marks & \( 20-30 \) & \( 30-40 \) & \( 40-50 \) & \( 50-60 \) & \( 60-70 \) & \( 70-80 \) \\
\hline No. of Students & 8 & 20 & 25 & 60 & 45 & 10 \\
\hline
\end{tabular}
