As part of its quality control program, the JudySmith Auto Company began inspecting all supplier shipments of steel bars and recording the defect rate according to quality criteria such as strength, dimensional characteristics, etc. When they began this program, the defect rate in 100 shipments averaged 9%. A recent report indicated an average defect rate of 2.5% in 200 shipments. The quality control department wants to determine, at the 0.05 level of significance, if this represents a significant improvement in the quality of the steel.

a.What is/are the parameter(s) of investigation?

b.State the null and alternative hypotheses.

c.Compute the test statistic.

d.State the corresponding p-value.

e.What is your conclusion for this test?