The development of the Internet has made many things possible, in addition to downloading music. In particular, it allows an increasing number of people to telecommute, or work from home. Although this has many advantages, it has required some companies to provide employees with the necessary equipment, which has made your job as office manager more difficult. Your company provides computers, printers, and Internet service to a number of engineers and programmers, and although the cost of hardware has decreased, the cost of supplies, in this case printer cartridges, has not. Because of the cost of name-brand printer replacement cartridges, several companies have entered the secondary market. You are currently considering offers from four companies. The prices are equivalent, so you will make your decision based on length of service, specifically number of pages printed.

You have given samples of four cartridges to 16 programmers and engineers and have received the following values:

Supplier A Supplier B Supplier C Supplier D 424 650 521 323 521 725 601 383 650 826 590 487 422 722 522 521

a. Using a significance level equal to 0.01, what conclusion should you reach about the four manufacturers’ printer cartridges? Explain.

b. If the test conducted in part a reveals that the null hypothesis should be rejected, which supplier should be used? Is there one or more you can eliminate based on these data? Use the appropriate test for multiple comparisons. Discuss.