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 line graph section is completely horizontal (flat). What does this indicate?
Show answer
Answer: The value is not changing
-
A pictograph uses ★ = 5 students. A bar shows ★★★★. How many students does it represent?
Show answer
Answer: 20
-
A graph shows revenue growing from $50,000 in 2020 to $80,000 in 2023. What is the total increase?
Show answer
Answer: $30,000
-
A pie chart is best used to show:
Show answer
Answer: Parts of a whole
Practice Questions
Test your knowledge of Graph & Chart Interpretation with a timed quiz. Answers are revealed at the end.
Take Quiz →