Answer:
By a factor 9
Explanation:
The intensity of a sound wave is proportional to the square of the amplitude of the wave:
[tex]I \propto A^2[/tex]
where
I is the intensity
A is the amplitude of the wave
In this problem, the amplitude of the sound wave is increased by a factor 3:
A' = 3A
So the intensity would change by
[tex]I' \propto A'^2 = (3A)^2 = 9 A^2 = 9I[/tex]
So, the intensity would increase by a factor 9.