11  Mean

\[ \mu = \frac{\sum_{i=1}^{n} x_i}{n} \]

(def numbers [1 17 4 -7 6 12 -15 4 10 12])

\[ \sum_{i=1}^{n} x_i \]

(apply + numbers)

44

\[ n \]

(count numbers)

10

\[ \frac{\sum_{i=1}^{n} x_i}{n} \]

(/ (apply + numbers) (count numbers))

22/5

(float (/ (apply + numbers) (count numbers)))

4.4

(defn mean [numbers]
  (float (/ (apply + numbers) (count numbers))))

(mean numbers)

4.4

11.1 Visualizing the mean

source: notebooks/mean.clj