401(k) Participation rates. Named for the section of the Internal Revenue Code that authorized them, 401(k) plans permit employees to shift part of their before-tax salaries into investments such as mutual funds. One company, concerned with what it believed was a low employee participation rate in its $401(k)$ plan, sampled 30 other companies with similar plans and asked for their $401(\mathbf{k})$ participation rates. The following rates (in percentages) were obtained.
$$
\begin{array}{llllllllllll}
\hline 80 & 76 & 81 & 77 & 82 & 80 & 85 & 60 & 80 & 79 & 82 & 70 \\
88 & 85 & 80 & 79 & 83 & 75 & 87 & 78 & 80 & 84 & 72 & 75 \\
90 & 84 & 82 & 77 & 75 & 86 & & & & & & \\
\hline
\end{array}
$$