Law of large numbers

Averages of repeated trials converge to the expected value

In probability theory, the law of large numbers is a mathematical law which states that the average of the results obtained from a large number of independent random samples converges to the true value, if it exists. More formally, the law of large numbers states that given a sample of independent and identically distributed values, the sample mean converges to the true mean. The law of large numbers is important because it guarantees stable long-term results for the averages of some random events.

From Wikipedia, under CC BY-SA. More on occurri.