8
If a wave has a wavelength of 9 meters and a period of 0.006, the velocity of the wave is 1500 m/s.
wavelength = wave velocity / frequency ,wavelength = c / f , 9 = c/(1/ 0.006) ,c = 9 *1/0.006 = 1500 m/s.
Added 9/28/2020 8:12:33 PM
This answer has been confirmed as correct and helpful.