Starter quiz
- Anything below the __________ represents 75% of the data.
- lowest value
- lower quartile
- median
- upper quartile ✓
- highest value
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- Anything below the lower quartile represents what percentage of the data?
- '25%' ✓
What is the range of the middle 50% of data?- '19 cm' ✓
- A wider box indicates data that is ______ consistent.
- 'less' ✓
Which class did better on average?- 'A' ✓
- Which class' scores were more consistent?
- 'B' ✓
Exit quiz
- Which of the following describe the interquartile range?
- Highest value lowest value
- Width of the box on a box plot ✓
- The difference between the upper and lower quartiles ✓
- ✓
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What is the interquartile range of the data represented on this box plot?- '16 cm' ✓
Calculate the interquartile range from this cumulative frequency graph.- '8' ✓
- What is the interquartile range of this set of data? 17, 13, 19, 21, 13, 14.
- '6' ✓
This table shows information about the heights of some year 7 and 11 pupils. Compare their heights by selecting the most useful statement.- The Y11 median and interquartile range are higher than Y7.
- On average the Y11 are taller and their heights are more consistent.
- On average the Y11 are taller and their heights are less consistent. ✓
- The Y11 median was higher, but the interquartile range is lower than Y7.
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This table shows information about the times some children and adults take to complete a puzzle. Compare their times by selecting the most useful statement.- On average the children did better and their times are more consistent.
- On average the children did better and their times are less consistent. ✓
- The children's median was lower and their interquartile range was higher.
- On average the adults did better and their times are less consistent.
- The adults' median was better and their interquartile range was lower.
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- The interquartile range tells us how spread out the middle 50% of the data is
- This can be seen visually with a box plot
- Box plots and cumulative frequency graphs can be compared
- This comparison involves the median and interquartile range
Common misconception
Not referring to the context of the question when comparing the data.
Highlight that just saying the median or the interquartile is bigger is of little use unless you know what the data was about.
Keywords
Interquartile range - Interquartile range is calculated by finding Q3 − Q1. This is because it is the range from the first to the third quartile.
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