A sound produces sound waves of time period 0.001s and wavelength 20cm .calculate the time taken by the sound waves to travel a distance of 800m

As the time period of the wave is given, T = 0.001 s
Therefore, the frequency of the wave, ? = 1/T = 1/0.001 = 1000 s-1

The velocity of the sound wave = ?? = 1000 ? 0.2 = 200 m s-1
Therefore, time taken by the sound wave to reach 800 m,
t = distance/velocity of sound wave = 800/200 = 4 s