##### Wikipedia Description

In colloquial language, an average is the sum of a list of numbers divided by the number of numbers in the list. In mathematics and statistics, this would be called the arithmetic mean. However, the word average may also refer to the median, mode, or other central or typical value. In statistics, these are all known as measures of central tendency . The most common type of average is the arithmetic mean. If n numbers are given, each number denoted by a i, where i =1,, n, the arithmetic mean is the sum of the a i 's divided by n or The arithmetic mean, often simply called the mean, of two numbers, such as 2 and 8, is obtained by finding a value A such that 2 + 8 = A + A. One may find that A =(2+8)/2 =5. Switching the order of 2 and 8 to read 8 and 2 does not change the resulting value obtained for A. The mean 5 is not less than the minimum 2 nor greater than the maximum8. If we increase the number of terms in the list to 2, 8, and 11, the arithmetic mean is found by solving for the value of A in the equation 2+8+11 = A + A + A. One finds that A =(2+8+11)/3 =7. https://en.wikipedia.org/wiki/Average