Two processes are used to produce forgings used in an aircraft wing assembly. Of 200 forgings selected from process 1, 10 do not conform to the strength specifications, whereas of 300 forgings selected from process 2,20 are nonconforming. a. Estimate the fraction nonconforming for each process.
b. Test the hypothesis that the two processes have identical fractions nonconforming. Use α = 0.05.
c. Construct a 90% confidence interval on the difference in fraction nonconforming between the two processes.