Where V is the velocity of the wave measure using ms. Of one wave to the crest of the next wave. So you can find the velocity of a wave with the frequency.
To calculate the frequency of a wave divide the velocity of the wave by the wavelength.
The symbol for wavelength is the Greek letter lambda l. The sound of splash is heard 313 seconds after the stone is dropped. Sound in water 1600 ms. Light in vacuum air 300000 kms.