The quality control manager at the Telektronic Company considers production of telephone-answering machines to be "out of control" when the overall rate of defects exceeds 4%. Testing of a random sample of 150 machines revealed that nine are defective, so the sample percentage of defects is 6%. The production manager claims that this is only a chance difference, so production is not really out of control and no corrective action is necessary. Use a 0.05 significance level to test the production manager's claim. Does it appear that corrective action is necessary?
Test the given claim, and draw the appropriate graph. Use the traditional method or the P-value method of testing hypotheses (or your instructor may specify which method to use with assigned exercises). Assume that all samples have been randomly selected.