Aptitude · Shapes and data
Charts and graphs, made easy
💡 The idea
Before reading any number, read the title, the axis labels and the units. Then ask what the chart is for: change over time (line), comparing groups (bar), parts of a whole (pie) or two numbers together (scatter).
Title and units→What kind of chart?→Read the values→Do the sum
🧭 The method: 3 steps
- Read the title, axis labels and units (thousands? %?).
- Check where the axis starts: not at 0 can exaggerate differences.
- Read the values you need, write them down, then calculate.
🎬 Every kind of question, in pictures
Pick a kind. Guess the answer first, then watch the picture work it out. Tap any step to see it in the picture.
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✏️ Worked examples
Example 1. An axis starts at 90. Bars show 95 and 100. How much bigger is the second, really?
- It LOOKS twice as tall (10 vs 5 above the axis)
- Really: 5 ÷ 95 × 100
⚡ Shortcut: About 5.3%
⚠️ Where people go wrong
- Ignoring “in thousands” on the axis.
- A cut-off axis makes small differences look huge.
- A scatter pattern shows things move together, not that one causes the other.
📌 Remember
- Time → line
- Groups → bar
- Parts of 100% → pie
- Two numbers → scatter