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)