A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of sound. What is the time interval between successive compressions from the source?

Given, 

Frequency of the sound, $\mathrm{\nu }$= 500 Hz 
distance of the person from the source = 450 m

Therefore,

Time interval between two successive compressions is given by, 

                T = $\frac{1}{\mathrm{\nu }} = \frac{1}{500} =0.002 s$