Answer:
v = 10 m / s
Step-by-step explanation:
For this exercise we will use the relationship between the speed of a wave and its frequency and wavelength
v = λ f
the wavelength is the distance at which the wave repeats, in this case the distance between the two ridges λ = 48 m.
the frequency is the number of oscillations per unit of time, it is also the inverse of the period which is the time in a complete oscillation, in this case they give us the time of half a period, ½ T = 2.4 s
T = 4.8 s
the frequency is
f = 1 / T
f = 1 / 4.8
f = 0.2083 Hz
let's calculate
v = 0.2083 48
v = 10 m / s