Two processes are used to produce forgings for an aircraft wing assembly. Of the 200 forgings selected from Process 1, 10 do not conform to the strength specifications, whereas of the 300 forgings selected from Process 2, 6 are nonconforming.
a) Estimate the fraction nonconforming in each process.
b) Can we conclude that fraction nonconforming delivered by Process 2 is at least 10% more than that yielded by Process 1? Use a significance level of 0.02.
c) Construct a 90% two-sided confidence interval onthe difference between the proportion nonconforming in processes 1 and 2. Based on this confidence interval, can you conclude at a significance level of 10% that the difference is not equal to 10%? Why?