What is the variance of 67, 70, 74, 75, 77, 68, 72, 76, 69, 72?
\(\large\sigma^2=\frac{\sum\limits_{i=1}^{n} (x_i-\overline x\ )^2 }{n-1} \)
\(n=10\)
\({\color{blue}\overline x}=\frac{\sum(67, 70, 74, 75, 77, 68, 72, 76, 69, 72)}{10}\color{blue}=72\)
\(\sum\limits_{i=1}^{10} (x_i-\overline x\ )^2 \) = (67-72)²+(70-72)²+(74-72)²+(75-72)²+(77-72)²+(68-72)²+(72-72)²+(76-72)²+(69-72)²+(72-72)²
=25+4+4+9+25+16+0+16+9+0
=108
\(\sigma^2=\frac{108}{10-1}=12\)
\(\sigma=\sqrt{12}=3.4641\)
\(The \ variance \ is \ \sigma =3.4641.\)
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