Interquartile range is calculated by finding Q3 − Q1. This is because it is the range from the first to the third quartile.

Interquartile range

Maths

In the prior unit, pupils compared two different sets of data. In this unit, pupils consider cumulative frequency graphs and histograms and compare these with other known graphical representations.

Graphical representations of data: cumulative frequency and histograms

The difference between the upper and lower quartiles

Which of the following describe the interquartile range?

What is the interquartile range of the data represented on this box plot?

Calculate the interquartile range from this cumulative frequency graph.

What is the interquartile range of this set of data?  17, 13, 19, 21, 13, 14.

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.

This table shows information about the heights of some year 7 and 11 pupils.  Compare their heights 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.

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.

Anything below the __________ represents 75% of the data.

Anything below the lower quartile represents what percentage of the data?

What is the range of the middle 50% of data?

A wider box indicates data that is {{ }} consistent.

Which class' scores were more consistent?

Starter Quiz