5 Each of a random sample of 200 steel bars taken from a production line was examined and 27 were found to be faulty.
- Find an approximate \(90 \%\) confidence interval for the proportion of faulty bars produced.
A change in the production method was introduced which, it was claimed, would reduce the proportion of faulty bars. After the change, each of a further random sample of 100 bars was examined and 8 were found to be faulty.
- Test the claim, at the \(10 \%\) significance level.