Wave speed, frequency and period
Wave speed equals frequency times wavelength, and period is simply one divided by frequency.
A worked example
A wave at 500 Hz with a wavelength of 0.30 m travels at 500 x 0.30 = 150 m/s, and its period is 1 / 500 = 0.0020 s.
The mistake people actually make
When a wave crosses into a new medium the frequency stays fixed and the wavelength changes with the speed. A pendulum's period, 2 pi times the square root of length over g, does not depend on the mass of the bob.