The geometric mean between two numbers is 12. If one number is 9, what is the other number?
Answer: B
Let the numbers be a and b. G.M. = \(\sqrt{ab} = 12\), so \(ab = 144\). Given one number a=9, we have \(9b = 144\), so \(b = 144/9 = 16\). The other number is 16.