Answer: (0.120,0.160)
Explanation:
Given : Sample size :

Number of disks were not defective =701
Then , the number of disks which are defective =

Now, the proportion of disks which are defective :

Significance level :

Critical value :

The confidence interval for population proportion is given by :-

Hence, the 90% confidence interval for the population proportion of disks which are defective = (0.120,0.160)