Given a set of statistical data, it is possible to represent the range, median and quartiles in one diagram known as a Box Plot or a Box and Whisker Plot.

**Example**

A survey was carried out to record the weekly wages of workers at a company.

The information is shown in the box plot diagram below.

State the lowest weekly wage, the highest, the lower quartile, the upper quartile, the median and the range.

**Answer**

We can read the median, the lower quartile, the upper quartile, the minimum and the maximum from the diagram as follows.

**Median = £280**

**Lower quartile = £250**

**Upper quartile = £350**

**Minimum = £150**

**Maximum = £500**

The** range** = Maximum - Minimum = 500 - 150 = **£350**

The **interquartile range** = Upper quartile - Lower quartile = 350 - 250 = **£100**