You make a spring wave with a wavelength of 1.5m. You Shake the spring with a frequency of 2hz. The speed of the wave is

(you have to slove it or fill in the blank I don't get it T.T HELP)

v = f \cdot \lambda

so \lambda = 1.5 m and since f = 2 Hz

\therefore v = 1.5 \cdot 2 = 3 m/s