Question

Calculation the Standard Deviation from the following set of 10 observations.

8, 9, 15, 23, 5, 11, 19, 8, 10 and 12

Answer 1

Table of calculation
Observation X	Deviation	Square of Deviation D2
8	– 4	16
9	–3	9
15	3	9
23	11	121
5	–7	49
11	–1	1
19	7	49
8	–4	16
10	–2	4
12	0	0
= 120		= 274

Number of observations = N = 10

(i) Mean = =

Mean of the observations = 12

(ii) Variance, = = 27.4

(iii)

On an average, the individual observations deviate from the arithmetic mean by 5.23.