Question

Eleven percent of the products produced by an industrial process over the past several months fail to conform to the specifications. The company modifies the process in an attempt to reduce the rate of the nonconformities. In a trial run, the modified process produces 24 nonconforming items out of a total of 300 produced.

a) Do these results demonstrate that the modification is effective? Support your conclusion with a test a significance at a significance level of 0.05.

b) Calculate a 95% confidence interval for the proportion of nonconforming items using the modified process. You will notice that your confidence interval would yield a different conclusion about the new process' significance. Explain what "yield[s] a different conclusion" means.

c) Why might the conclusion from the interval in part b) differ from the conclusion from the significance test in part a)?

Answer 1