Inspection of a random sample of 28 aircraft showed that 17 needed repairs to fi
ID: 3356578 • Letter: I
Question
Inspection of a random sample of 28 aircraft showed that 17 needed repairs to fix a wiring problem that might compromise safety.
(a) How large a sample would be needed to estimate the true proportion of jets with the wiring problem, with 95 percent confidence and an error of ± 6 percent? (Enter your answer as a whole number (no decimals). Use a z-value taken to 3 decimal places in your calculations.)
Sample size
(b) Would the airline actually conduct further sampling, or just inspect all the planes?
Inspect all the planes Conduct further samplingExplanation / Answer
a)
here estimated proportion phat=17/28=0.607
margin of error E =0.06
for 95% Confidence interval ; critical value of z =1.96
hence required sample size n=p(1-p)*(Z/E)2 =~255
b)
as this is concerning safety as well cost of Jet is very high;
therefore Inspect all the planes is correct option.