Charts and graphs · Grade 8
In Grade 8 you learn: histograms and frequency polygons.
Charts turn a table of numbers into a picture you can read at a glance. Bar charts compare separate groups. Pie charts show how a whole is shared out. Line graphs show how something changes over time.
Key facts
- Pie chart: the whole circle (360°) is the total. Angle = frequency/total × 360°.
- Frequency from a pie chart = angle/360° × total.
- Line graph: plot a point for each time and join them; steeper means faster change.
- Check the scale: an axis that does not start at 0 can make small differences look big.
Worked examples
Example 1
60 people chose a drink: tea 25, coffee 20, juice 15. Work out the angles for a pie chart.
Answer: Tea 150°, coffee 120°, juice 90°