Question

The diagram shows waves of sound travelling through the air. By which factor is the sound intensity decreased at 3 meters?

Answer 1

The diagram is missing; however, we know that the intensity of a sound wave is inversely proportional to the square of the distance from the source:
$I(r)= \frac{1}{r^2}$
where I is the intensity and r is the distance from the source.

We can assume for instance that the initial distance from the source is r=1 m, so that we put 
$I= \frac{1}{r^2}= \frac{1}{(1)^2}=1$
The intensity at r=3 m will be
$I= \frac{1}{r^2}= \frac{1}{(3)^2}= \frac{1}{9}$
Therefore, the sound intensity has decreased by a factor $1/9$.

Answer 2

its a  on edge just finished my exam

heres the diagram