### Measures of dispersion - (16.1-16.3)

#### Understand the concepts of range and inter-quartile range

• Find the range and inter-quartile range for each of the following sets of data.
(a) 1, 4, 9, 16, 25, 36, 49
(b) 22, 5, 17, 28, 33, 8, 19, 11
• $$\begin{array}{l}(a)Range = 49 - 1 = \underline{\underline {48}} \\{Q_1} = 4 \\{Q_3} = 36 \\Inter-quartile range = 36 - 4 = \underline{\underline {32}} \end{array}$$

(b) Arrange the data in ascending order as follows:
5, 8, 11, 17, 19, 22, 28, 33

$$\begin{array}{l} Range= 33 - 5 = \underline{\underline {28}} \\{Q_1} = \frac{{8 + 11}}{2} = 9.5 \\{Q_3} = \frac{{22 + 28}}{2} = 25 \\Inter-quartile range = 25 - 9.5\\ = \underline{\underline {15.5}} \end{array}$$