Start with the case question before doing any calculation. Ask what decision the chart is supposed to help you make.

Then identify the key comparison or relationship in the exhibit. You may need a growth rate, margin, share, absolute difference, or weighted average, but only if that calculation helps answer the decision.

A useful sequence is: read the axes and units, state the main pattern, explain the implication, then calculate only what is missing to support that implication.

Avoid calculating every number you can see. This CaseBasix guide to case interview graphs and charts gives you a structured way to practice that sequence. See case interview graphs and charts.

This is a good example of where a full-case debrief is more useful than just checking whether the final answer was right.