We can think this through intuitively. A frequency of 256 Hz means that the wave has 256 cycles each second. If the wavelength is 1.33 meters, then there are 256 of them each second. Therefore, we just need to multiply the wavelength by the frequency to find the speed of sound. (Note that the units Hz = 1 / s)
v = (frequency) x (wavelength)
v = (256 Hz) x (1.33 m)
v = 340.5 m/s
The speed of sound in the vicinity of the fork is 340.5 m/s
