The formula for the commonly used mean (the so-called "arithmetic mean") is
ð ə WORD_BOUNDARY f ɔ ɹ m j ʊ l ə WORD_BOUNDARY f ə ɹ ð ə WORD_BOUNDARY k ɑ m ə n l i WORD_BOUNDARY j uː z d WORD_BOUNDARY m iː n WORD_BOUNDARY ð ə WORD_BOUNDARY s oʊ k ɔ l d WORD_BOUNDARY ə ɹ ɹ ɪ θ m ə t ɪ k WORD_BOUNDARY m iː n WORD_BOUNDARY ɪ z WORD_BOUNDARY