When the population size is finite, as in the case of a waterfront 

 facility, the equation for the number of required samples can be modified 

 to include a term accounting for the population size as follows: 



z p(l - p) 



+1 



•l 



(10) 



Again, as the population size (N) gets larger, Equation 10 reduces 

 to the expression in Equation 9. Figure 2 shows a family of curves 

 depicting the percentage of samples required for a finite versus an 

 infinite population as a function of the population size. 



Frequency and Probability Distributions 



Distributions in statistical analysis are important because they 

 provide a way of summarizing variations in observed data. The dis- 

 tributions deal with expectations and are used to make inferences and 

 decisions under conditions of uncertainty. Three distributions of 

 importance to this discussion are the frequency, probability, and 

 cumulative distribution functions. 



1000 1500 



Population Size, N 



Figure 2. Percentage of samples required for a finite 

 versus infinite population. 



