In $7-9,$ find the mean, median, range, and interquartile range for each set of data to the nearest tenth.
$$
\begin{array}{|c|c|}\hline x_{i} & {f_{i}} \\ \hline 50 & {3} \\ {45} & {8} \\ {40} & {12} \\ {35} & {15} \\ {30} & {11} \\ {25} & {7} \\ {20} & {4} \\ \hline\end{array}
$$