# Insert two geometric means between 4 and 256 .

$\begin{array}{1 1} 8,16 \\ 32,128 \\ 16,128 \\ 16,64 \end{array}$

Answer : (d) 16,64
Explanation : $4,g_{1},g_{2},256\; are\;in\;GP$
$4,4r,4r^2,256.$
$4\;.r^3=256$
$r^3=\large\frac{256}{4}=64\quad \;r=4$
$GM=4r\;\xi\;4r^2=4*4\;\xi\;4*4*4$
$=16\;\xi\;64.$
answered Jan 3, 2014 by
edited Jan 24, 2014