10 12 14 16 IB 20 

 Wave Height, Crest to Tfough, feet 



Figure 2b - Cumulative Distribution Function 



Figure 2- Distribution of Heights of Ocean Waves at Weather Station C, 

 52° N 37° W, North Atlantic Ocean 



This distribution is based on 12,365 observations made over a period of 4V4 years by 

 U.S. Weather Bureau personnel. 



Mathematically 



r r 



P{x) = I pdx and P (a; -» oo) = I pdx = 1 

 •' 



[11 



P is a function of x, and this function is designated as the cumulative distribution function 

 (c.d.f.) of X. P{x) is numerically equal to the probability that a value chosen at random from 

 the population- is less than x. 



