When a positive value is repeated in either the means or extremes position of a proportion, that value is referred to as a **geometric mean** (or **mean proportional**) between the other two values.

**Example 1:** Find the geometric mean between 4 and 25.

Let *x* = the geometric mean.

The geometric mean between 4 and 25 is 10.

**Example 2:** 12 is the geometric mean between 8 and what other value?

Let *x* = the other value.