A car horn has a frequency of 680 Hz and a wavelength of 50cm. Calculate the speed of the sound waves produced by the car horn:

velocity (v) = frequency of the wave (f) x wavelength of wave (in metres) (λ)
50cm in metres: 50/100 = 0.5m
Therefore (v) = 680 x 0.5= 340 (m/s)