Question

18. Given the table of measurements 24 29 32 25 26 25 28 29 30 30 28 27 28 26 27 30 29 29 27 28 28 27 26 27 29 31 27 28

Answer 1

The mean is calculated as for the sample

24	26	30	28	29	28	29
25	29	27	30	28	27	28
29	25	30	26	29	27	31
32	28	28	27	27	26	27

$\bar{X}=\frac{X1+X2+X3....X28}{28}=\frac{25+25+.....32}{28}=27.854$

Sample standard deviation calculated as

$S=\frac{\sum (\bar{X}-X_{i})}{N-1}$

X_i= Sample elements

S=1.8602

Now

The spread of samples

$\bar{X}\pm3S$

From 25.994 to 29.7142

Hence the spread under this value will be

26
26
26
27
27
27
27
27
27
28
28
28
28
28
28
29
29
29
29
29