Graph & Chart Interpretation
Reading and analysing bar charts, line graphs, and pie charts
Explanation
Types of Graphs
| Graph Type | Best Used For |
|---|---|
| Bar chart | Comparing categories |
| Line graph | Showing change over time |
| Pie chart | Showing proportions of a whole |
| Pictograph | Simple frequency using symbols |
| Stem-and-leaf plot | Distribution of data values |
Reading Bar Charts
- Check the y-axis scale and increment carefully
- For double bar charts, use the legend to distinguish categories
- Difference between two bars = read each value then subtract
Reading Pie Charts
- Each slice is a fraction or percentage of the whole (360°)
- A slice of 90° = 90 ÷ 360 = 25% of the total
- If the total count is given, slice % × total count = that category's count
Reading Line Graphs
- Steeper gradient = faster rate of change
- Horizontal section = no change during that period
- To find a value between plotted points, interpolate (estimate between marks)
Key Questions the Exam Asks
- What is the highest / lowest value, and which category?
- What is the difference between two values?
- What is the total or average across all categories?
- What is the trend? (increasing, decreasing, steady)
Key Tips
- Always read axis titles and units before reading data values
- Check if the y-axis starts at 0 — a truncated axis exaggerates differences
- For pictographs, each symbol may represent more than 1 unit — always check the key
Sample Practice Questions
-
A bar chart shows: Maths=45, English=30, Science=35, Art=20. How many students chose Maths and Science combined?
Show answer
Answer: 80
-
A line graph is most useful for showing:
Show answer
Answer: Change over time
-
A line graph section is completely horizontal (flat). What does this indicate?
Show answer
Answer: The value is not changing
-
On a bar chart, the tallest bar represents the:
Show answer
Answer: Highest value
Practice Questions
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What does Graph & Chart Interpretation cover in the Selective Entry Numerical Reasoning exam?
Reading and analysing bar charts, line graphs, and pie charts.
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