ﻗﺎﻧﻮﻥ ﻣﻴﺎﻧﮕﻴﻨﻬﺎ

law of averages:قانون احتمالات

Please see the Wiki page: "The law of averages is a layman's term for a belief that the statistical distribution of outcomes among members of a small sample must reflect the distribution of outcomes across the population as a whole.

As invoked in everyday life, the "law" usually reflects wishful thinking or a poor understanding of statistics rather than any mathematical principle. While there is a real theorem that a random variable will reflect its underlying probability over a very large sample, the law of averages typically assumes that unnatural short-term "balance" must occur.[1] Typical applications of the law also generally assume no bias in the underlying probability distribution, which is frequently at odds with the empirical evidence.[citation needed]"

سوال تکراری است http://www.proz.com/kudoz/english_to_farsi_persian/military_...
ولی معادل انتخابی اشتباه است
قانون متوسط‌ها http://www.aftabir.com/dictionaries/word/148424/قانون