Spherical sound waves: distance for amplitude to drop by factor of 2.10

[cmilho10]

A jackhammer, operated continuously at a construction site, behaves as a point source of spherical sound waves. A construction supervisor stands 63.5 m due north of this sound source and begins to walk due west. How far does she have to walk in order for the amplitude of the wave function to drop by a factor of 2.10?

Could someone point me in the right direction on solving this please?

 

[wormhole]

i hope i right

take origin as place where jackhammer is
$y_0$ is where supervisor at the beginning.
you know that amplidute falls with the distance as $\frac{A_0}{r}$

assume that supervisor walks in positive x direction distance s

 

[cmilho10]

ok...but I'm still confused about what to do with these relationships and the numbers given in the problem

 

[wormhole]

$$\frac{A_0}{r}=2.1$$
=>$r=\frac{A_0}{2.1}$

finaly

$$y_0^2+x^2=r^2=(\frac{A_0}{2.1})^2$$