Wave velocity (V)= 0.3 m s^{-1}

frequency (f) = 20 Hz

wavelength (λ) = ?

As we know,

Wave velocity (V) = Frequency (f) × Wavelength (λ)

Substituting the values, we get,

0.3 = 20 × λ

⇒ λ = 0.3\over 20 = 1.5 × 10^{-2} m

Hence, **the separation between the two consecutive compressions which is the wave length = 1.5 x 10 ^{-2} m ( or 1.5 cm)**