Data Representation
Charts and graphs convert collected values into forms that are easier to compare and interpret.
Choosing a representation
- A bar chart compares discrete categories.
- A pie chart shows parts of a whole; sector angle = frequency ÷ total × 360°.
- A histogram represents continuous grouped data using adjoining bars; class intervals and scale must be labelled.
Worked examples
- If 12 of 40 learners prefer football, the pie-chart angle is 12/40 × 360° = 108°.
- For frequencies 5, 8 and 7, the total is 20; the second category represents 8/20 = 40%.
- A histogram for height intervals must place intervals on the horizontal axis and frequency on the vertical axis.
Practice
- Construct a pie chart for frequencies 10, 15 and 5.
- Explain one difference between a bar chart and a histogram.
- Interpret a chart by identifying the largest category and calculating its proportion.
