Sigman Corporation makes batteries that are used in highway signals in rural areas. The company…

Sigman Corporation makes batteries that are used in highway signals in rural areas. The company managers claim that the median life of a battery exceeds 4,000 hours. To test this claim, they have selected a random sample of n = 12 batteries and have traced their life spans between installation and failure. The following data […]

A cable television customer call center has a goal that states that the median time for each…

A cable television customer call center has a goal that states that the median time for each completed call should not exceed four minutes. If calls take too long, productivity is reduced and other customers have to wait too long on hold. The operations manager does not want to incorrectly conclude that the goal isn’t […]

A recent trade newsletter reported that during the initial 6-month period of employment, new sales..

A recent trade newsletter reported that during the initial 6-month period of employment, new sales personnel in an insurance company spent a median of 119 hours per month in the field. A random sample of 20 new salespersons was selected. The numbers of hours spent in the field by members in a randomly chosen month […]

At Hershey’s, the chocolate maker, a particular candy bar is supposed to weigh 11 ounces. However,..

At Hershey’s, the chocolate maker, a particular candy bar is supposed to weigh 11 ounces. However, the company has received complaints that the bars are under weight. To assess this situation, the company has conducted a statistical study that concluded that the average weight of the candy is indeed 11 ounces. However, a consumer organization, […]

Sylvania’s quality control division is constantly monitoring various parameters related to its…

Sylvania’s quality control division is constantly monitoring various parameters related to its products. One investigation addressed the life of incandescent light bulbs (in hours). Initially, they were satisfied with examining the average length of life. However, a recent sample taken from the production floor gave them pause for thought. The data follow: Their initial efforts […]

The Penn Oil Company wished to verify the viscosity of its premium 30-weight oil. A simple random…

The Penn Oil Company wished to verify the viscosity of its premium 30-weight oil. A simple random sample of specimens taken from automobiles running at normal temperatures was obtained. The viscosities observed were as follows: Determine if the median viscosity at normal running temperatures is equal to 30 as advertised for Penn’s premium 30-weight oil. […]

The Cell Tone Company sells cellular phones and airtime in several states. At a recent meeting, the.

The Cell Tone Company sells cellular phones and airtime in several states. At a recent meeting, the marketing manager stated that the median age of its customers is less than 40. This came up in conjunction with a proposed advertising plan that is to be directed toward a young audience. Before actually completing the advertising […]

The Wilson Company uses a great deal of water in the process of making industrial milling equipment.

The Wilson Company uses a great deal of water in the process of making industrial milling equipment. To comply with federal clean-water laws, it has a water purification system that all wastewater goes through before being discharged into a settling pond on the company’s property. To determine whether the company is complying with federal requirements, […]

For each of the following tests, determine which of the two U statistics 1U1 or U22 you would…

For each of the following tests, determine which of the two U statistics 1U1 or U22 you would choose, the appropriate test statistic, and the rejection region for the Mann–Whitney test: The following sample data have been collected from two independent samples from two populations. Test the claim that the second population median will exceed […]

The following sample data have been collected from independent samples from two populations. The…

The following sample data have been collected from independent samples from two populations. The claim is that the first population median will be larger than the median of the second population. a. State the appropriate null and alternative hypotheses. b. Using the Mann–Whitney U-test, based on the sample data, what should you conclude about the […]