Question

If the arithmetic mean and harmonic mean between two numbers are $27$ and $12$ respectively, then the geometric mean of those two numbers is

• A. $9$
• B. $14$
• C. $18$
• D. $24$

Answer 1

The correct option is C $18$

Let $A,G$ and $H$ be the A.M., G.M. and H.M. respectively,
We know that,
$G^2=AH\Rightarrow G^2=27\times 12\therefore G=\sqrt{27\times 12}=18$