Required Tasks:
1. Develop histograms showing the distribution of rivet diameters from the two suppliers.
2. Compute the sample means and standard deviations for the two sets of data.
3. Comment on whether it appears the assumptions required for testing if the two populations have equal mean diameters are satisfied.
4. Select a level of significance for testing whether the two suppliers have rivets with equal mean diameters. Discuss the factors you used in arriving at the level of significance you have selected.
5. Perform the appropriate null and alternative hypothesis test. Discuss the results.
6. Prepare a short report outlining your recommendation.
Cregg Hart is manufacturing manager for Motive Power Company, a locomotive engine and rail car manufacturer. The company has been very successful in recent years, and in July 2006 signed two major contracts totaling nearly $200 million. A key to the company’s success has been its focus on quality. Customers from around the world have been very pleased with the attention to detail put forth by Motive Power.
One of the things Cregg has been adamant about is that Motive Power’s suppliers also provide high quality. As a result, when the company finds good suppliers, it stays with them and tries to establish a long-term relationship. However, Cregg must also factor in the costs of parts and materials and has instructed his purchasing staff to be on the lookout for “better deals.”