The arithmetic mean of a set of observed data is equal to the sum of the numerical values of each observation, divided by the total number of observations.
ðɪ ɚɹˈɪθmətˌɪk mˈiːn əvə sˈɛt ʌv əbzˈɜːvd dˈeɪɾə ɪz ˈiːkwəl tə ðə sˈʌm ʌvðə nuːmˈɛɹɪkəl vˈæljuːz ʌv ˈiːtʃ ɑːbzɚvˈeɪʃən, dᵻvˈaɪdᵻd baɪ ðə tˈoʊɾəl nˈʌmbɚɹ ʌv ɑːbzɚvˈeɪʃənz.