ðɪ ɚɹˈɪθmətˌɪk mˈiːn ʌv ˌɛni ɐmˈaʊnt ʌv ˈiːkwəlsˈaɪzd nˈʌmbɚ ɡɹˈuːps təɡˌɛðɚɹ ɪz ðɪ ɚɹˈɪθmətˌɪk mˈiːn ʌvðɪ ɚɹˈɪθmətˌɪk mˈiːnz ʌv ˈiːtʃ ɡɹˈuːp.
The arithmetic mean of any amount of equal-sized number groups together is the arithmetic mean of the arithmetic means of each group.