Sections of aluminum sheet metal of various lengths,used for construction of airplane fuselages, are lined up on a conveyor belt that moves at a constant speed. Asample is selected by taking whatever section is passingin front of a station at five-minute intervals. Explain why this sample may not be random; that is, it is not an accu-rate representation of the population of all aluminum sections.

Two popular brands of tires for tractor-trailers are the Puma and the Eternal. Salma is a buyer for a major shipping company and wants to determine if there is any difference between the two brands of tire in the mean distance (in thousands of km) driven on them before they need to be replaced. In the company's testing lab, Salma tests a random sample of 14 Puma tires and a random sample of 15 Eternal tires. (These samples are chosen independently.) For the Puma tires, the sample mean distance (in thousands of km) until they would need to be replaced is 54.71 with a sample variance of 5.95. For the Eternal tires, the sample mean distance (in km) until they would need to be replaced is 50.21 with a sample variance of 37.75. Assume that the two populations of distances driven are approximately normally distributed. Can Salma conclude, at the 0.05 level of significance, that there is a difference between the population mean of the distances (in thousands of km) driven on Puma tires before…

An adventure company runs two obstacle courses, Fundash and Coolsprint. The designer of the courses suspects that the mean completion time of Fundash is not equal to the mean completion time of Coolsprint. To test this, she selects 205 Fundash runners and 300 Coolsprint runners. (Consider these as random samples of the Fundash and Coolspring runners.) The 205 Fundash runners complete the course with a mean time of 76.7 minutes and a standard deviation of 5.3 minutes. The 300 Coolsprint runners complete the course with a mean time of 77.5 minutes and a standard deviation of 5.1 minutes. Assume that the population standard deviations of the completion times can be estimated to be the sample standard deviations, since the samples that are used to compute them are quite large. At the 0.05 level of significance, is there enough evidence to support the claim that the mean completion time, ,, of Fundash is not equal to the mean completion time, μ₂, of Coolsprint? Perform a two-tailed test.…

An adventure company runs two obstacle courses, Fundash and Coolsprint, with similar designs. Since Fundash was built on rougher terrain, the designer of the courses suspects that the mean completion time of Fundash is greater than the mean completion time of Coolsprint. To test this, she selects 235 Fundash runners and 275 Coolsprint runners. (Consider these as independent random samples of the Fundash and Coolspring runners.) The 235 Fundash runners complete the course with a mean time of 78.1 minutes and a standard deviation of 6.7 minutes. The 275 individuals complete Coolsprint with a mean time of 76.4 minutes and a standard deviation of 8.1 minutes. Assume that the population standard deviations of the completion times can be estimated to be the sample standard deviations, since the samples that are used to compute them are quite large. At the 0.01 level of significance, is there enough evidence to support the claim that the mean completion time, u,, of Fundash is greater than…

Among 1815 randomly selected high school students surveyed by the Centers for Diseases Control, 300 said they were current smokers. b. Estimate the variability in such sample proportion by finding SE (p).

An amusement park keeps track of the percentage of individuals with season passes according to age category. An independent tourist company would like to show that this distribution of age category for individuals buying season passes is different from what the amusement park claims. The tourist company randomly sampled 200 individuals entering the park with a season pass and recorded the number of individuals within each age category. Age Category Child (under 13 years old) Teen (13 to 19 years old) Adult (20 to 55 years old) Senior (56 years old and over) Number of Individuals 56 86 44 14 The tourist company will use the data to test the amusement park’s claim, which is reflected in the following null hypothesis. H0:pchild=0.23H0:pchild=0.23, pteen=0.45pteen=0.45, padult=0.20padult=0.20, and psenior=0.12psenior=0.12. What inference procedure will the company use to investigate whether or not the distribution of age category for individuals with season passes is…

he Princeton Review, a company that tracks information about various colleges, reports that 30% of CofC students are out-of-state students.   If we took many samples of CofC students, and for each sample calculate the proportion $\hat{p}$ of out-of-state students in that sample, what would be the center of this distribution?

Consider a random sample of 300 students in a university, 75 of them declared that they like playing football. Compute a point estimate of the proportion of all students who would like to play football.

A local nursery specializes in custom-designed landscaping for residential areas. The estimated labor cost associated with a particular landscaping proposal is based on the number of plantings of trees, shrubs, and so on to be used for the project. For cost-estimating purposes, managers use 2.2 hours of labor time for planting of a medium-sized tree. A random sample of 36 tree plantings is selected and the planting times are recorded. The average planting time for the sample of 36 planting is 2.7 hours with a standard deviation of .9 hours. The researcher wants to test if the average planting time is significantly greater than 2.2 hours based on the data that was collected. Họ: H= 2.2 H1: u> 2.2 What is the value of the Test Statistic for this hypothesis test? Round Z to the 100ths place.

Researchers have been studying acorns produced by trees in a certain region. The acorns are used as a food source by various animals. The researchers have recorded the mass of a random sample of acorns (displayed below). Acorn mass (grams): 4.1, 4.22, 3.9, 3.79, 4.09, 4.1, 4.03, 4.02, 3.78, 3.74, 3.72 Checksum: 43.49 Resample the sample (bootstrap) (link to program) with 1000 iterations to create a 90% confidence interval for the mean mass of all acorns: Result: The researchers can be 90% confident that the mean mass of all acorns in this region is between and grams.