A questionnaire was given to students in an introductory statistics class during the first week of the course. One question asked, "How stressed have you been in the last [tex]$2 \frac{1}{2}$[/tex] weeks, on a scale of 0 to 10, with 0 being not at all stressed and 10 being as stressed as possible?" The students' responses are shown in the frequency distribution below. How many students were involved in the study?
Frequency Distribution
\begin{tabular}{|c|c|}
\hline
Stress Rating & Frequency \\
\hline
0 & 6 \\
\hline
1 & 3 \\
\hline
2 & 4 \\
\hline
3 & 11 \\
\hline
4 & 14 \\
\hline
5 & 20 \\
\hline
6 & 15 \\
\hline
7 & 29 \\
\hline
8 & 31 \\
\hline
9 & 10 \\
\hline
10 & 16 \\
\hline
\end{tabular}