Find the geometric mean between the given two numbers.
3 and 108
To find geometric mean, the first thing you need to do is multiply your original numbers together.
108 x 3 = 324. Then what you do next is find the square root of 328, or the number gathered from what you multiplied. The square root of 324 is 18, therefore your answer and the geometric mean between 108 and 3 is A. Hope this helps. :)
Edit: For a more official way of showing your work:
x = √ab
x = √(108 x 3)
x = √324
x = 18