Answer: 216
Step-by-step explanation:
The formula to find the sample size , if prior population proportion is known :-
[tex]n=p(1-p)(\dfrac{z_{\alpha/2}}{E})^2[/tex]
Given : The prior proportion of defective parts : p= 0.10
Significance level : [tex]\alpha=1-0.95=0.05[/tex]
Critical value : [tex]z_{\alpha/2}=1.96[/tex]
Margin of error : [tex]E=0.04[/tex]
Now, the required sample size will be :-
[tex]n=0.1(0.9)(\dfrac{(1.96)}{0.04})^2=216.09\approx216[/tex]
Hence, the minimum required sample size = 216