Mean

Updated 28 Sep 2026

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What it is
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  the arithmetic average — the sum of all data values divided by the count of data values
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Formula
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  $\bar{x}=\dfrac{1}{n}\sum_{i=1}^{n}x_i$
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Grouped-data formula
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  $\bar{x} = \dfrac{1}{N}\sum (F \times T)$ , where $F$ is each class's frequency and $T$ is its midpoint
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Example
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  for a frequency table with $\sum(F{\times}T) = 372.1$ and $N=20$ : $\bar{x} = 372.1/20 = 18.605$
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Grouped-data interpretations
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  using class midpoints $m_i$ , $\bar{x}\approx\dfrac{\sum_i f_i m_i}{\sum_i f_i}$
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  this is an approximation to the original-data mean unless the midpoint substitution happens to preserve the relevant total
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Related
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  Measures of Central Tendency
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  Median

Linked references 5