Build the concept, interpret evidence, and apply it in a separate assessment pool.
Learn: Evidence and decisions
Pie charts show parts of one whole
First identify the total represented by the circle. A category amount is its percentage multiplied by that total. Add category percentages when the question asks for a combined share.
Stacked charts show components and totals
Each segment represents one component. The full column height is the sum of all components. Compare segment heights for component questions and complete column heights for total questions.
Match the denominator to the question
Equal percentages can represent different amounts when the totals differ. Keep the chart’s population, period, or unit attached to every calculation.
Overlapping groups require disjoint regions
In a Venn diagram, each region has a separate count. A set total includes its exclusive region and the overlap. At least one is the union; exactly one excludes the overlap; neither is outside both sets. For a conditional statement, restrict the denominator to the specified group. Circle size is schematic unless a quantitative area scale is explicitly stated.
Convert each share using its own whole
Multiply the displayed fraction or percentage by the total named in the prompt. Add shares before multiplying when the question asks for combined categories.
Check the parts sum to the whole
The displayed shares of a complete pie must total 100%. If the categories are exhaustive, the remaining share is 100% minus the listed shares.
Learning Objectives
Interpret a pie slice as a fraction of one stated total.
Convert a percentage share into an amount.
Read each stacked component from its segment and the whole from the cumulative column height.
Compare shares and amounts without confusing their denominators.
Distinguish union, intersection, exactly one, and neither.
Compute conditional proportions from a restricted Venn population.
Use the answer choices and wording to distinguish a share, an amount, a difference, and a conditional proportion.
Prerequisite Knowledge
Percent means “per 100.”
For stacked columns, each segment adds to the segments below it.
Worked Examples
Convert a pie-chart share to an amount
Category B occupies a fraction of the total shown on the pie chart.
Distribution of 400 units
Convert the share into an amount.0.45×400=180 units
Interpret with the stated unit.
Conclusion: Report the resulting amount with the unit shown on the chart.
Read a stacked-column total
A stacked column contains North and South components; determine the full column total.
Regional deliveries by quarter■ North■ South
Read the axis labels, scale and units before comparing values.
Add the two components to get the full column total.55+35=90
Conclusion: The sum is the full column total; a single component is not the total.
Change the denominator in a Venn diagram
The survey has 100 employees. Find the proportion with at least one certification and the proportion of Finance-certified employees who also hold Analytics certification.
Employee certification survey
Numbers are counts in separate regions: first set only, both sets, second set only, neither. Circle areas are not proportional to counts.
Add the three regions inside at least one circle. Count the overlap once.30+20+25=75,P(A∪F)=10075=75%
Restrict the denominator to the Finance circle for the conditional proportion.P(A∣F)=20+2520=94
Check the total using all four disjoint regions.30+20+25+25=100
Conclusion: At least one means the union. Both means the overlap. A conditional probability changes the population used in the denominator.
Find a category amount and a combined amount
A pie chart displays A=15%, B=35%, and C=50% of 600 applications.
Multiply B’s share by the total.0.35(600)=210
Combine A and C shares before converting to an amount.(0.15+0.50)(600)=0.65(600)=390
Conclusion: B represents 210 applications; A and C together represent 390.
A percentage can describe money or a count
A $240,000 budget is divided into Digital 20%, Events 30%, and Research 50%.
Apply each share to the stated dollar total.0.20(240,000)=48,000
Combine non-digital categories using their combined share.(0.30+0.50)(240,000)=192,000
Conclusion: Digital receives $48,000 and Events plus Research receive $192,000.
Think Like a GMAT Test-Taker
Read the title, total, legend, and units before calculating.
For a pie chart, multiply the share by the matching total.
For stacked columns, add segments when asked for a total; read only one segment when asked for a component.
Label the four disjoint regions, then translate the wording before adding counts.
Read the prompt and its completion choices before calculating; attach the stated total and population to every share.
For an “at least one” question, add disjoint regions once; for a “both” question, use only the overlap.
Common Traps
Reporting a percentage when the question asks for an amount.
Comparing amounts across circles with different totals using percentages alone.
Mistaking one stacked segment for the whole column.
Counting the overlap twice when finding at least one.
Using the full survey total for a conditional probability.
Treating circle area as a count without a stated scale.