Final answer:
A pie chart is best for displaying the percentage contribution of each category to the whole, as it visually represents parts of a whole. Bar graphs, including Pareto charts, are better for comparing actual numbers or showing changes over time.
Step-by-step explanation:
If Sarah wants to focus on and display the percentage contribution that each category makes to the whole, a pie chart would be the most effective choice. Pie charts are specifically designed to show parts of a whole, making it easy to compare the relative size of each category as a percentage of the entire dataset.
In contrast, although bar graphs can indicate percentages, they are better suited for comparing the counts or measuring changes over time. Sarah should ensure that her pie chart has distinct, easily distinguishable colors for each category, and that the percentages are legible to effectively communicate the data to her boss.
Bar graphs can still display percentages, but they are preferable when you wish to see the actual numbers or compare values across categories clearly. A Pareto chart, which is a type of bar graph, can be useful because it arranges categories in descending order, making it easier to see which categories are the most significant at a glance.