Answer
4.8
Work Step by Step
The intensity is given by equation 11–18, $I=2 \pi^2 \rho v f^2 A^2$. If the only difference between the waves is their frequencies, then the ratio of the intensities is the ratio of the square of the frequencies.
Let “1” label the lower-frequency sound wave, and “2” label the higher-frequency wave.
$$\frac{I_2}{I_1}=\frac{(2.2f)^2}{f^2}\approx 4.8$$