Chapter 11 Data Analysis and Statistics - 11.1 Find Measures of Central Tendency and Dispersion - 11.1 Exercises - Skill Practice - Page 748: 24a

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The mean when the outlier is included: $\bar x=\frac{70+55+54+75+60+58+55+6+62+68+94+55+82+69+74}{12}=62.06\\\sigma=\sqrt \frac{5288.9376}{16}=18.1813$ Since $|\frac{6-62.06}{18.1813}|\approx3.0834\gt3$, 6 is an outlier.