Quartiles, Percentiles, and Box Plots
Ages 16–18Difficulty adapts to you
Quartiles, Percentiles, and Box Plots
Quartiles divide ordered data into four parts: Q1 is the lower quartile, Q2 is the median, and Q3 is the upper quartile. The interquartile range is IQR = Q3 − Q1. A box plot uses minimum, Q1, median, Q3, and maximum; its shape helps compare centre and spread.
Your goals
- ✓You can find positions in ordered data and compare distributions with five-number summaries.
- ✓You can use Quartiles, Percentiles, and Box Plots, model correctly.
- ✓You can use the definitions, units, assumptions, and examples to check your answer.
Words to know
- Quartiles, Percentiles, and Box Plots:
- Find positions in ordered data and compare distributions with five-number summaries.
- model:
- A rule or representation used to describe a situation and make a prediction.
Examples
- 1For 2, 4, 5, 7, 9, 12, 15, Q2 = 7; lower half gives Q1 = 4 and upper half gives Q3 = 12, so IQR = 8.
- 2A long upper whisker suggests greater spread among the larger values.
Check these
- • Do not skip the meaning of a term or give a result without explaining what it means.
- • Keep every number, symbol, label, and unit in its correct place.
- • Show enough working to check how you reached your answer.
Helpful habits
- • Read the whole question before choosing what to do.
- • Show one clear step at a time and check each step.
- • If you are stuck, draw a model, try smaller numbers, or revisit the example.
Now try your own
Create your own quartiles, percentiles, and box plots example, solve it, and explain how you checked it.
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Helpful Hints“Double-check your work before moving on.”