Step-by-step explanation:
the velocity of sound in air is 330m/s
and v=fh, where h is wavelength f is frequency,
h=v/f.......(1)
longer wavelength
h=330/20,h=16.5m
shorter wavelength
h=330/20000,h=1.65x10-²m
The lesser frequency was used for finding the longer wavelength since wavelength is inversely proportional to frequency,
thus an increase in frequency brings a decrease in wavelength.
and shorter wavelengths are more high and intense
hope this helps