Two teams of workers assemble aircraft navigational systems at a manufacturing plant in Washington. Team 2 uses a new costly manufacturing system that management is considering for the entire operation. A random sample of 150 assemblies from team 1 shows 21 unacceptable assemblies. A similar random sample of 125 assemblies from team 2 shows 12 unacceptable assemblies.
(A) Is there sufficient evidence to conclude, at the 10% significance level, that the new manufacturing system reduces the number of unacceptable assemblies? Conduct the appropriate hypothesis test.
(B) Is there sufficient evidence to conclude, at the 5% significance level, that the new manufacturing system reduces the number of unacceptable assemblies? Conduct the appropriate hypothesis test.
(C) Calculate the p-value and explain how to use it for testing the null hypothesis.
(D) Would you recommend that the firm invest in the new system?