A wildlife study is designed to find the mean weight of salm

A wildlife study is designed to find the mean weight of salmon caught by an (text not clear) company. As a preliminary study, a random sample of 250 freshly caught is weighted. The sample standard deviation of the weights of these 250 fish is 2.35 ib. how larg a sample should be taken to be 99% confident that the sample mean is within 0.20 ib of the true mean weight.

Solution

Note that      
      
n = z(alpha/2)^2 s^2 / E^2      
      
where      
      
alpha/2 = (1 - confidence level)/2 =    0.005  
      
Using a table/technology,      
      
z(alpha/2) =    2.575829304  
      
Also,      
      
s = sample standard deviation =    2.35  
E = margin of error =    0.2  
      
Thus,      
      
n =    916.030412  
      
Rounding up,      
      
n =    917   [ANSWER]