Which graph is most suitable for displaying the distribution of exam scores into equal-width intervals?

• A. Line graph
• B. Bar graph
• C. Histogram
• D. Stem and leaf plot

Answer: (C)

Using a histogram to display exam scores makes the distribution easy to read. It groups the numerical scores into consecutive, equal-width intervals (for example, 0–9, 10–19, 20–29, and so on) and uses a bar for each interval with height equal to how many scores fall into that range. This setup highlights the shape of the distribution—the most common score ranges, whether scores cluster toward one end, and if there are gaps or outliers. The bars touch, signaling the continuous nature of scores rather than separate categories.

A line graph is meant for showing how something changes over time or another ordered sequence, not for comparing how many scores fall into value ranges. A bar graph compares distinct categories, which is more appropriate for qualitative data rather than a continuous numerical distribution. A stem-and-leaf plot also shows distribution but is best for smaller data sets and doesn’t present the distribution across broad equal-width intervals as clearly as a histogram.