Charts and diagrams
Charts and diagrams
| Chart | What it shows |
|---|---|
| bar chart | a bar per category; height = frequency |
| pie chart | a circle split into slices, each a fraction of $360^{\circ}$ |
| pictogram | a symbol stands for a number of items |
| stem-and-leaf | keeps the digits of ordered data, with a key |
Practice
On a bar chart, the height of each bar shows the:
Bar height represents the frequency of that category.
Pie chart slices
- Each slice is its fraction of $360^{\circ}$.
- Worked example: of $120$ people, $30$ chose tea → slice $= \dfrac{30}{120}\times 360^{\circ} = 90^{\circ}$.
Practice
Out of 120 people, 30 chose tea. Find the angle of the tea slice on a pie chart (degrees).
(30/120) × 360 = 90°.
Practice
Out of 160 people, 40 chose juice. Find the angle of the juice slice (degrees).
(40/160) × 360 = 90°.
You've got it
Key idea
- bar chart height = frequency; pictogram uses a symbol for several items
- pie chart: each slice $= \dfrac{\text{part}}{\text{total}}\times 360^{\circ}$
- $\dfrac{30}{120}\times 360^{\circ} = 90^{\circ}$