Wavelength, Frequency & Wavespeed?

Question

ocean waves, which travel in the open sea at 5m/s, arrive at the beach once every 4s.
1) calculate the distance between the wave crests in the open sea
2)calculate how long these waves would take to reach the beach if they were formed in a storm 1200km away. (answer in hours)

Answer 1

Wavelength = lambda
Velocity = v
Frequency = f
Period T = 1/f
Relations among these parameters:
v = lambda*f = lambda/T
1) Looking for lambda, given v and T
lambda = vT = 5 m/s * 4 s = 20 m
2) Travel time = x/v = 1,200,000 (m) / 5 (m/s) = 240,000 s. You can get the hours.

Answer 2

Don't bother ..... just run.