As purchasing agent for the Horner-Williams Company, you have primary responsibility for securing high-quality raw materials at the best possible price.

One particular material that the Horner-Williams Company uses a great deal of is aluminum. After careful study, you have been able to reduce the prospective vendors to two. It is unclear whether these two vendors produce aluminum that is equally durable.

To compare durability, the recommended procedure is to put pressure on the aluminum until it cracks. The vendor whose aluminum requires the greatest average pressure will be judged to be the one that provides the most durable product.

To carry out this test, 14 pieces from vendor 1 and 14 pieces from vendor 2 are selected at random. The following results in pounds per square inch (psi) were noted:

Before testing the hypothesis about difference in population means, suppose the purchasing agent for the company was concerned about whether the assumption of equal population variances was satisfied.

a. Based on the sample data, what would you tell him if you tested at the significance level of 0.10?

b. Would your conclusion differ if you tested at the significance level of 0.02? Discuss.

c. What would be the largest significance level that would cause the null hypothesis to be rejected?

Transcribed Image Text:

Vendor 1 14 =2,345 psi $1 = 300 Vendor 2 m = 14 =2,411 psi $2 = 250