Question

A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective.

Step 2 of 2 :  

Suppose a sample of 322 floppy disks is drawn. Of these disks, 306 were not defective. Using the data, construct the 90% confidence interval for the population proportion of disks which are defective. Round your answers to three decimal places.

Answer 1

We have given,              
              
x=322-306=16          
n=322          
Estimate for sample proportion=0.0497  
Level of significance is =1-0.90=0.1      
Z critical value(using Z table)=1.645      
              
Confidence interval formula is              


=(0.030,0.070)