If different values of variable x are 9.8, 5.4, 3.7, 1.7, 1.8, 2.6, 2.8, 8.6, 10.5 and 11.1; find

(i) the mean $\overline{x}$

(ii) the value of $∑(x - \overline{x})$

(i) Given:

The observation are 9.8, 5.4, 3.7, 1.7, 1.8, 2.6, 2.8, 8.6, 10.5 and 11.1.

Mean = $\dfrac{\text{Sum of all observations }}{\text{Number of all observations }}$

= $\dfrac{9.8 + 5.4 + 3.7 + 1.7 + 1.8 + 2.6 + 2.8 + 8.6 + 10.5 + 11.1}{10}$

= $\dfrac{58}{10}$

= 5.8

Hence, the mean $\overline{x}$ = 5.8.

(ii)

$∑(x - \overline{x})$ = 4 + (-0.4) + (-2.1) + (-4.1) + (-4) + (-3.2) + (-3) + 2.8 + 4.7 + 5.3

= 4 - 0.4 - 2.1 - 4.1 - 4 - 3.2 - 3 + 2.8 + 4.7 + 5.3

= 0

Hence, $∑(x - \overline{x})$ = 0.