Here are the shopping times (in minutes) for each of sixteen shoppers at a local grocery store.
\begin{tabular}{|lllllllll|}
\hline \multicolumn{8}{|c|}{\begin{tabular}{c}
Shopping times \\
(in minutes)
\end{tabular}} \\
\hline 33 & 30 & 23 & 31 & 18 & 34 & 19 & 28 \\
35 & 27 & 26 & 24 & 29 & 31 & 16 & 18 \\
\hline
\end{tabular}
(a) Complete the grouped frequency distribution for the data. (Note that the class width is 4 .)
\begin{tabular}{|c|}
\hline \begin{tabular}{c}
Shopping times \\
(in minutes)
\end{tabular} \\
16 to 19 \\
20 to 23 \\
24 to 27 \\
28 to 31 \\
32 to 35 \\
\hline
\end{tabular}
(b) Construct a histogram for the data.

Step 1 ：Count the number of shopping times that fall into each of the given intervals. The counts are as follows: \(16 \text{ to } 19: 3\), \(20 \text{ to } 23: 1\), \(24 \text{ to } 27: 3\), \(28 \text{ to } 31: 5\), \(32 \text{ to } 35: 4\)

Step 2 ：Complete the grouped frequency distribution with the counts. The completed grouped frequency distribution is: \begin{tabular}{|c|c|} \hline \begin{tabular}{c} Shopping times \\ (in minutes) \end{tabular} & Frequency \\ \hline 16 to 19 & 3 \\ 20 to 23 & 1 \\ 24 to 27 & 3 \\ 28 to 31 & 5 \\ 32 to 35 & 4 \\ \hline \end{tabular}

Step 3 ：To construct a histogram for the data, use the intervals as the x-axis and the frequencies as the y-axis. Each interval is represented by a bar, and the height of the bar corresponds to the frequency of that interval. The x-axis would have the intervals (16-19, 20-23, 24-27, 28-31, 32-35). The y-axis would have the frequencies (3, 1, 3, 5, 4). There would be a bar for each interval, with the height of the bar corresponding to the frequency. For example, the bar for the interval 28-31 would be the tallest, since it has the highest frequency of 5.