A box-and-whisker plot is used to

• A. To highlight the most frequent value
• B. To display the distribution of data through quartiles and extremes
• C. To track changes in data over time
• D. To compare sums across groups

Answer: (B)

A box-and-whisker plot shows how data are spread and where most values lie by displaying quartiles and the extremes. The box represents the middle 50% of the data—from the first quartile to the third quartile—with a line inside the box marking the median. The whiskers extend to the minimum and maximum values (or to the most extreme non-outlier values), and any outliers may appear as individual points. This layout lets you quickly see the center, the spread, and any skew in the data. It’s not about the most frequent value (that’s a histogram or mode), it doesn’t track changes over time (that’s a line graph), and it isn’t primarily used to compare sums across groups (that’s a bar chart). So it’s best understood as a display of the distribution through quartiles and extremes.