The geometric mean of 8 and 32

A geometric mean is the n-th root of the product of n numbers.

In this case, there are 2 numbers, which means you take the square root. If there were 3 numbers, you'd take the cube-root, and so on...

First, multiply 8 and 32 to get 256. Now, take the square root of 256, which is 16. This is the geometric mean.