In this guide
A chart is a table drawn as a picture, and the picture can mislead. Two bars that look almost equal can differ by 10%. A line that climbs steeply may show a smaller percentage rise than a gentle one higher up the axis. A stacked segment that looks taller may be smaller, because it starts higher.
CAT uses exactly these gaps between appearance and value. This guide shows how to read each chart type, then works through a two-chart set. Since this page cannot show images, the charts are given as tables of the values you would read off them.
First, read the frame
Before any value, check four things.
- The scale. Does the axis start at zero? A bar chart whose axis starts at 80 makes a 90-to-100 rise look like a doubling.
- The units. Crores, lakhs, thousands of tonnes, percentages?
- Two axes. Charts that combine bars and a line often use a separate axis for the line. Read each series against its own axis.
- Labelled or unlabelled values. If the values are printed on the bars, use them. If not, read to the nearest gridline and expect options that are spaced apart enough to allow for this.
Chart types and how to read them
| Chart | What it shows best | How to read it | Classic trap |
|---|---|---|---|
| Simple bar | Comparison across categories or years | Read each bar's value | Axis not starting at zero |
| Grouped bar | Two or more series side by side | Compare within a group, then across | Mixing series colours |
| Stacked bar | Parts of a total | Each segment = top boundary − bottom boundary | Reading a segment's top as its value |
| Line | Change over time | Values at points; slope = absolute change | Treating slope as percentage growth |
| Bar plus line | Two related measures | Each series against its own axis | Reading the line on the bar axis |
Slope is not growth rate
On a line chart, the steepness between two points shows the absolute change. The percentage change also depends on where the line starts. A rise from 135 to 162 and a rise from 108 to 135 are both 27 units and look equally steep, but the first is 20% and the second 25%.
Reading stacked bars
Suppose a stacked bar chart shows the sales of three models, X, Y and Z (thousand units). The readings below are the tops of each segment, which is what your eye picks up from the chart.
| Year | Top of X | Top of Y | Top of Z (bar total) |
|---|---|---|---|
| 2023 | 30 | 55 | 70 |
| 2024 | 36 | 56 | 80 |
The segments are the differences:
| Year | X | Y | Z | Total |
|---|---|---|---|---|
| 2023 | 30 | 55 − 30 = 25 | 70 − 55 = 15 | 70 |
| 2024 | 36 | 56 − 36 = 20 | 80 − 56 = 24 | 80 |
Y's top edge rose from 55 to 56, yet Y's sales fell from 25 to 20, a 20% drop. Z grew from 15 to 24, a 60% rise. A glance at the chart would suggest neither.
Worked set: a company over six years
A bar chart shows a company's revenue and cost (₹ crore) from 2019 to 2024. A line chart on a second axis shows its number of employees. The values read from the charts are below.
| Year | Revenue (₹ crore) | Cost (₹ crore) | Employees |
|---|---|---|---|
| 2019 | 120 | 100 | 400 |
| 2020 | 108 | 96 | 360 |
| 2021 | 135 | 110 | 375 |
| 2022 | 162 | 126 | 450 |
| 2023 | 180 | 150 | 480 |
| 2024 | 198 | 160 | 495 |
Profit is revenue minus cost. Build the derived rows once, then answer.
| Year | Profit (₹ crore) | Profit margin | Revenue growth | Cost growth | Revenue per employee (₹ lakh) |
|---|---|---|---|---|---|
| 2019 | 20 | 16.67% | – | – | 30.0 |
| 2020 | 12 | 11.11% | −10% | −4% | 30.0 |
| 2021 | 25 | 18.52% | +25% | +14.58% | 36.0 |
| 2022 | 36 | 22.22% | +20% | +14.55% | 36.0 |
| 2023 | 30 | 16.67% | +11.11% | +19.05% | 37.5 |
| 2024 | 38 | 19.19% | +10% | +6.67% | 40.0 |
Revenue per employee: ₹120 crore ÷ 400 = ₹0.3 crore = ₹30 lakh, and so on.
Cost growth in 2021 and 2022 looks almost identical: (110 − 96) ÷ 96 = 14.58% and (126 − 110) ÷ 110 = 14.55%. The same absolute rise over a slightly larger base gives a slightly smaller percentage.
Q1. In which year was profit the highest? 2024 (₹38 crore).
Q2. In which year was the profit margin the highest? 2022 (36 ÷ 162 = 22.22%). Highest profit and highest margin are different years, which is the point of asking both.
Q3. In which year was the percentage growth in revenue the highest? 2021 (25%). Revenue rose by ₹27 crore in both 2021 and 2022, so a chart reader who compares bar increments sees a tie. The lower base in 2021 makes its percentage higher.
Q4. In how many years from 2020 to 2024 was the percentage change in cost higher than the percentage change in revenue? 2.
- 2020: cost −4% against revenue −10%. Cost fell less, so its change is higher. Counts.
- 2023: cost +19.05% against revenue +11.11%. Counts.
- 2021, 2022 and 2024: revenue grew faster.
It is easy to miss 2020 because both figures fell. "Higher" applies to negative numbers too: −4 is higher than −10.
Q5. In how many years did revenue per employee rise compared with the previous year? 3 (2021, 2023 and 2024). It stayed at ₹30 lakh in 2020 and ₹36 lakh in 2022, and "rise" excludes no change.
Q6 (TITA). What was the company's total profit over the six years, in ₹ crore? 161 (20 + 12 + 25 + 36 + 30 + 38).
Common errors
- Absolute versus percentage change. Check what the question asks. "Highest increase" without "percentage" usually means absolute; if unsure, read the options.
- The wrong base year. Growth in 2023 is measured against 2022, not 2019.
- Stacked segments. Always subtract the lower boundary.
- Dual axes. Read the line against its own scale.
- "Rise" versus "did not fall". No change is neither a rise nor a fall.
Practice set
Use the six-year table above.
- Which two years had the same profit margin?
- By what percentage did revenue grow from 2019 to 2024?
- What was the cost per employee in 2024, to the nearest ₹0.1 lakh?
- In which year was profit per employee the highest?
Answers:
- 2019 and 2023. 20 ÷ 120 and 30 ÷ 180 are both 1/6, or 16.67%.
- 65%. (198 − 120) ÷ 120 = 78 ÷ 120 = 0.65.
- ₹32.3 lakh. ₹160 crore ÷ 495 = ₹0.3232 crore.
- 2022. Profit per employee: 2019 ₹5 lakh, 2020 ₹3.33 lakh, 2021 ₹6.67 lakh, 2022 ₹8 lakh, 2023 ₹6.25 lakh, 2024 ₹7.68 lakh. The year of highest total profit (2024) is not the year of highest profit per employee.
What to do next
- For every chart set this week, first convert the chart into a table of values, as done above.
- Practise ten stacked-bar readings: write each segment as top minus bottom.
- In each chart set, list the derived quantities (profit, margin, per-head values) before you read the questions.
- Continue with pie charts, and revisit table-based DI for gap-filling and fraction benchmarks.
A note on dates and numbers. Exam patterns, vacancies and schedules change from year to year. Always confirm the current details in the latest notification on the Indian Institutes of Management website .
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