A sound wave of the form s = sm cos(kx - ωt + Ψ) travels at 345 m/s through air in a long horizontal tube. At one instant, air molecule A at x = 2.01 m is at its maximum positive displacement of 6.00 nm and air molecule B at x = 2.11 m is at a positive displacement of 2.40 nm. All the molecules between A and Bare at intermediate displacements. What is the frequency of the wave?