Average is a number that is typical of a group of numbers. It provides one measure of the center of the numbers. People often think of an average as a mean, or arithmetic average. A mean is the sum of a group of numbers divided by the number of numbers in the group. For example, the average, or mean, of 4, 5, 5, 7, and 14 is 7—that is, 35 (the sum of the five numbers) divided by 5 (the number of numbers).
Other numbers are also typical of a group of numbers, including the median and the mode. A median is the middle number of a series of numbers arranged in numerical order, but only if there is an odd number of such numbers. If the number of numbers is even, the median is the mean of the middle two numbers. The mode is the number that occurs most often in a group. In the given example, the median and mode are both 5. See also Mean ; Median ; Mode ; Statistics (Probability) .
