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The median of a increasing sorted sequence of n numbers a_1 ≤ a_2 ≤ a_3 ≤ ... ≤ a_n is: - for odd n: a term in middle, - for even n: an arithmetic mean of two terms in middle. Example I. Example II. Grades. Sorted. Median. Why is the median a better description of the data than the arithmetic mean? Example. The salaries in some firm: owner $12000, secretary $9000, workers $700, $700, $1000, $1100, $1200. The arithmetic mean: (12000 + 9000 + 700 + 700 + 1000 + 1100 + 1200) / 7 ≈ $3671. The increasing sorted salaries: $700, $700, $1000, $1100, $1200, $9000, $12000. Median: $1100. In the above example it is showed that the median ($1100) is better description of the salaries in this firm than the arithmetic mean ($3671).