The average, in general, means the average value of a group of numerical observations— or the statistical measure of the arithmetic mean (or just the mean). On a scale of measurement, it is usually the place in which the population is centered. Numerically, it equals the sum of the scores divided by the number of scores. For example, the sum of 3, 7, 10, 15, and 25 is 60; thus, the mean is 60 divided by 5, or 12. The geometric mean is another type of mean: For two quantities, it is the square root of the quantities’ product; the notation is for *n* quantities, and the geometric mean is the *n*th root of their product.