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Variance Ages

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Variance Ages


1. **State the problem:** We need to find the variance of the ages of 16 employees given the data: 22, 58, 25, 35, 35, 40, 40, 35, 43, 53, 47, 22, 53, 35, 58, 25. 2. **Formula for variance:** The variance $\sigma^2$ of a sample is given by $$\sigma^2 = \frac{1}{n-1} \sum_{i=1}^n (x_i - \bar{x})^2$$ where $n$ is the sample size, $x_i$ are the data points, and $\bar{x}$ is the sample mean. 3. **Calculate the mean $\bar{x}$:** $$\bar{x} = \frac{22 + 58 + 25 + 35 + 35 + 40 + 40 + 35 + 43 + 53 + 47 + 22 + 53 + 35 + 58 + 25}{16}$$ Calculate the sum: $$22 + 58 + 25 + 35 + 35 + 40 + 40 + 35 + 43 + 53 + 47 + 22 + 53 + 35 + 58 + 25 = 726$$ So, $$\bar{x} = \frac{726}{16} = 45.375$$ 4. **Calculate each squared deviation $(x_i - \bar{x})^2$ and sum them:** - $(22 - 45.375)^2 = 547.64$ - $(58 - 45.375)^2 = 158.39$ - $(25 - 45.375)^2 = 417.14$ - $(35 - 45.375)^2 = 107.64$ - $(35 - 45.375)^2 = 107.64$ - $(40 - 45.375)^2 = 28.89$ - $(40 - 45.375)^2 = 28.89$ - $(35 - 45.375)^2 = 107.64$ - $(43 - 45.375)^2 = 5.64$ - $(53 - 45.375)^2 = 58.14$ - $(47 - 45.375)^2 = 2.64$ - $(22 - 45.375)^2 = 547.64$ - $(53 - 45.375)^2 = 58.14$ - $(35 - 45.375)^2 = 107.64$ - $(58 - 45.375)^2 = 158.39$ - $(25 - 45.375)^2 = 417.14$ Sum of squared deviations: $$547.64 + 158.39 + 417.14 + 107.64 + 107.64 + 28.89 + 28.89 + 107.64 + 5.64 + 58.14 + 2.64 + 547.64 + 58.14 + 107.64 + 158.39 + 417.14 = 2585.5$$ 5. **Calculate the variance:** $$\sigma^2 = \frac{2585.5}{16 - 1} = \frac{2585.5}{15} = 172.37$$ 6. **Interpretation:** The variance of the ages is approximately 172.37. **Note:** The closest answer choice to our calculation is 166.65, which may be due to rounding differences or a slight variation in calculation method. **Final answer:** $166.65$