Benson Manufacturing is considering ordering electronic components from three different suppliers. The suppliers may differ in terms of quality in that the proportion or percentage of defective components may differ among the suppliers. To evaluate the proportion defective components for the suppliers, Benson has requested a sample shipment of 500 components from each supplier. The number of defective components and the number of good components found in each shipment is as follows.

Component	A	B	C
Defective	15	20	45
Good	485	480	455

a. Formulate the hypotheses that can be used to test for equal proportions of defective components provided by the three suppliers.

1. H 0: p 1 p 2 = p 3

2. H 0: p 1 = p 2 = p 3

3. H 0: p 1 p 2 p 3

Choose correct answer from above choice 2 H

a: Not all population proportions are equal

b. Using a .05 level of significance, conduct the hypothesis test. What is the p-value? Use Table 12.4.

The p-value is less than or equal .05

What is your conclusion?

Conclude that the three suppliers do not provide equal proportions of defective components.

c. Conduct a multiple comparison test to determine if there is an overall best supplier or if one supplier can be eliminated because of poor quality. Round p i, p j and difference to two decimal places. Round critical value to four decimal places.

Comparison	p i	p j	Difference	n i	n j	Critical Value	Significant Diff
A vs B				500	500		NO
A vs C				500	500		YES
B vs C	0.04	0.09	0.05	500	500	0.0380	YES