GMAT · Graphics Interpretation · TOPIC LESSON
Decode the visual encoding before comparing, estimating or extending a pattern.
BY THE END, YOU CAN
BEFORE YOU START
Original educational lesson. Work through the examples before revealing the practice answers. This original lesson supports current GMAT study through an editorial skill map. It does not reproduce official questions, predict exam content or guarantee a score.
LEARN THROUGH ORIGINAL PRACTICE
All passages, examples and exercises here are original. No official GMAC questions, choices or explanations are reproduced. This independent preparation resource is not affiliated with or endorsed by GMAC. GMAT is a trademark of the Graduate Management Admission Council.
01 / UNDERSTAND & APPLY
Graphics Interpretation converts a picture into constrained statements, often completed with dropdown selections. Before reading values, identify the horizontal and vertical variables, units, tick spacing, legend and whether the figure reports observations or a model. A large visual gap may reflect scale design rather than a large substantive effect.
All figures here use original fictional data. The first figure has two separate panels: regional counts North 40, South 60 and West 100 orders; and daily output at days 0,1,2,3 of 20,35,30,50 units. Lines connect daily observations as a visual guide, without asserting constant production between measurements.
Full-size scientific diagram. Swipe or scroll horizontally; keyboard users can focus the diagram and use arrow keys.
ORIGINAL WORKED EXAMPLE
First figure: Which region has the largest order count, and on which observed day is output lowest? Give both answers.
Answer West; day 0
02 / UNDERSTAND & APPLY
A bar’s length encodes a magnitude, so a zero baseline normally makes direct length comparison meaningful. A truncated baseline can exaggerate apparent ratios. A line chart emphasizes ordered movement and can use a nonzero scale if clearly labeled; read values rather than comparing filled areas.
Connected points do not by themselves prove smooth change between observations. Distinguish a fall in the displayed variable from a fall in its rate of growth: output can increase while its growth slows.
ORIGINAL WORKED EXAMPLE
First figure: From day 1 to day 2, what is the change in output and the percentage change relative to day 1?
Answer −5 units; approximately −14.29%
ORIGINAL PRACTICE · 1
20; 100
South−North=60−40=20, and the West bar is 100. These are two response parts of one exercise.
03 / UNDERSTAND & APPLY
A pie chart encodes proportions through sectors. Identify the total and check that categories partition it: mutually exclusive and collectively exhaustive categories sum to 100%. Overlapping memberships should not be forced into a pie without a clear partition rule.
The original pie uses 200 orders: online 50%, phone 30%, counter 20%. Sector angles are proportional to shares, but an exact label is preferable to measuring a rendered angle.
Full-size scientific diagram. Swipe or scroll horizontally; keyboard users can focus the diagram and use arrow keys.
ORIGINAL WORKED EXAMPLE
Pie panel: How many orders were placed by phone, and by how many did online orders exceed counter orders?
Answer 60 phone orders; 60 more online than counter
ORIGINAL PRACTICE · 1
72°
The counter share is 20%, so its angle is 0.20×360°=72°. This uses the part-to-whole encoding; no protractor is needed.
04 / UNDERSTAND & APPLY
Each point in a scatter plot represents one paired observation, not a category total. Read both coordinates together. An upward association means larger x tends to accompany larger y in the displayed data; it does not prove x causes y or that every successive point rises.
In the scatter panel, the observed pairs are (1,4),(2,8),(3,10),(4,10), with x operating hours and y parcels processed. The supplied fitted line is y=2x+3. It summarizes a trend; observed points need not lie on it.
ORIGINAL WORKED EXAMPLE
Scatter panel: At 3 hours, what is the observed count and the fitted-line prediction?
Answer Observed: 10; fitted: 9 parcels
ORIGINAL PRACTICE · 1
No
Observed counts are 4,8,10,10. The final pair is equal, despite an overall positive association.
05 / UNDERSTAND & APPLY
For y=mx+b, slope m=(change in predicted y)/(change in x). Units matter: parcels per operating hour differ from parcels. The intercept is the model’s value at x=0 and may fall outside the observed range.
If axes use different physical scales, a 45-degree line is not necessarily slope 1. Compute from labeled coordinates, not the angle on a screen. A fitted relationship may be useful within the data range without being reliable outside it.
ORIGINAL PRACTICE · 1
4 parcels
The horizontal change is 2 hours and slope is 2 parcels/hour, so predicted rise=2×2=4 parcels.
ORIGINAL PRACTICE · 2
No
The intercept 3 is a feature of the supplied fitted model. No observation at x=0 is shown, and a model extrapolation is not a measured fact.
06 / UNDERSTAND & APPLY
A distribution groups observations by value or interval. In a histogram with equal-width bins, bar heights can represent counts. With unequal-width bins and density axes, area rather than height may represent frequency; always inspect the label.
The original wait-time histogram has counts 4 in [0,5), 8 in [5,10), 6 in [10,15), and 2 in [15,20] minutes, a total of 20 observations. Brackets include an endpoint; parentheses exclude it. Exact values within each bin are not supplied.
Full-size scientific diagram. Swipe or scroll horizontally; keyboard users can focus the diagram and use arrow keys.
ORIGINAL WORKED EXAMPLE
Histogram panel: What fraction waited less than 10 minutes, and can the exact median wait be determined?
Answer 60%; exact median cannot be determined
ORIGINAL PRACTICE · 1
[5,10) minutes; 8 observations
That bin has the greatest frequency, 8. The grouped data do not identify the most frequent exact wait time.
07 / UNDERSTAND & APPLY
In a pictograph, one symbol can represent several units. Count symbols and multiply by the key. Partial symbols must be defined; do not assume a half-icon is decorative or represents one item.
The companion pictograph assigns one filled circle to 10 available seats. Room R has 3 circles and Room S has 5, representing 30 and 50 seats. These are seat counts, not the number of people currently present.
ORIGINAL PRACTICE · 1
80
There are 3+5=8 symbols, each worth 10 seats, so total=80 seats. Eight is the symbol count, not the seat count.
08 / UNDERSTAND & APPLY
A main time chart and a magnified inset can show the same variable at different temporal resolutions. Compare their explicit time labels and units before comparing visual slopes. A minute in the inset is not an hour in the overview.
The original overview reports temperature at 00:00,06:00,12:00,18:00,24:00 as 10,10,14,14,12°C. The inset adds measurements at 12:00,12:15,12:30 of 14,17,14°C. Straight overview connectors do not rule out the short spike seen in the inset.
Full-size scientific diagram. Swipe or scroll horizontally; keyboard users can focus the diagram and use arrow keys.
ORIGINAL PRACTICE · 1
(i) No; (ii) Yes
The 12:15 observation is 17°C, refuting (i). From 12:00 to 12:15, 17−14=3°C, supporting (ii). The coarse endpoints alone hide the intervening change.
09 / UNDERSTAND & APPLY
Interpolation estimates within the observed x range; extrapolation extends beyond it. Both rely on a model or assumption about the relationship, but extrapolation additionally assumes that the relationship continues outside the available data.
For the daily-output line, estimating day 1.5 by straight-line interpolation gives (35+30)/2=32.5 units under a linear-between-points assumption. It is not an observed output. Extending the last rise to day 4 would add 20 to predict 70, but the graph alone does not establish that extension.
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