Question

An environmentalist wants to find out the fraction of oil tankers that have spills each month.

Step 2 of 2 :  

Suppose a sample of 516 tankers is drawn. Of these ships, 393 did not have spills. Using the data, construct the 90% confidence interval for the population proportion of oil tankers that have spills each month. Round your answers to three decimal places.

Answer 1

We have given,              
              
x=516-393=123          
n=516          
Estimate for sample proportion=0.2384  
Level of significance is =1-0.90=0.1      
Z critical value(using Z table)=1.645      
              
Confidence interval formula is              


=(0.208,0.269)
              
Lower limit for confidence interval=0.208  
              
Upper limit for confidence interval=0.269