The solution for this problem is:
A velocity of wave is given as V = λ⋅f
V - velocity of wave
f - frequency of wave
λ - wave length
So getting the wave length is:
λ = V/f
λminimum = V / fmaximum
λminimum = 342 / 4200
λminimum = 0.081 m
λmaximum = V/ fminimum
λmaximum = 342 / 28
λmaximum = 12.214 m