A shift of one fringe in the Michelson-Morley experiment would result from a difference of one wavelength or a change of one period of vibration in the round-trip travel of the light when the interferometer is rotated by 90°. What speed would Michelson have computed for Earth's motion through the ether had the experiment seen a shift of one fringe? (The orbital speed of Earth is 29.8 km/s and the expected number of fringes in the Michelson-Morley experiment is 0.4.)