The formula for determining frequency of a wave is expressed as
f = v/λ
where
λ is the wavelength
f is the frequency
v is the velocity
From the information given,
v = 2.8
λ = 1.3
a) f = 2.8/1.3
frequency = 2.15 Hz
b)
Period = i/frequency
Period = 1/2.15
Period = 0.47 s
