Solution :
Let, intensity at distance 3 m from the acoustic source is [tex]I_o[/tex].
We need to find the distance d where the intensity is [tex]\dfrac{I_o}{2}[/tex].
Now, we know intensity is inversely proportional to square of distance between the source.
[tex]\dfrac{I_o}{\dfrac{I_o}{2}} = \dfrac{d^2}{3^2}\\\\d^2 = 18 \\\\d = 3\sqrt{2}\ m[/tex]
Therefore, intensity will be halved at a distance of [tex]3\sqrt{2}\ m[/tex].
