In: Statistics and Probability
A poll is taken in which 348 out of 525 randomly selected voters
indicated their preference for a certain candidate.
(a) Find a 99% confidence interval for p.
≤. p. ≤.
(b) Find the margin of error for this 99% confidence interval for
p.
We have given,          
   
          
   
x=348          
n=525          
Estimate for sample proportion=  
0.6629  
Level of significance is =0.01      
Z critical value(using Z table)=2.576  
a)   
      
Confidence interval formula is      
       
=(0.6098, 0.7160)
          
   
Lower limit for confidence interval=0.6098  
          
   
Upper limit for confidence interval=0.7160  
(b)
=0.0531
Margin of error E=0.0531