question

"Snoqualmie" is a name shared by a waterfall and a tribe of Native Americans. In a study of the cultural importance of the waterfall, two groups of the Snoqualmie tribe were randomly surveyed. One group consisted of Snoqualmie members living less than 25 miles from the waterfall. Another group consisted of Snoqualmie members living more than 25 miles from the waterfall. The researchers asked each member to rate the cultural importance of the waterfall as low, medium, or high. Data from the study are presented in the following table. If the distributions of ratings are the same for those Snoqualmie members living less than 25 miles from the waterfall and those living more than 25 miles from the waterfall, which of the following is equal to the expected count of members living less than 25 miles from the waterfall who rated the cultural importance as high?

answer

E. ((17)(50)/88)

question

Horseshoe crabs on a beach can be overturned by approaching waves. These "stranded" crabs may right themselves by turning over. During a period of many days on an Atlantic Ocean beach, investigators categorized a random sample of crabs as either stranded or not stranded and additionally noted their age category. The researchers wanted to investigate whether there is convincing evidence of an association between becoming stranded and age. Data from their study are shown in the following table. If becoming stranded and age are independent in these creatures, which of the following is closest to the expected number of young stranded horseshoe crabs?

answer

B. 52.54

question

Juvenile ground squirrels respond to predators by making "alarm calls" that can alert others to danger. A biologist conducted a study to investigate how squirrels respond to these alarm calls: run to burrow or freeze. The biologist played recordings of alarm calls for three samples of ground squirrels, grouped by age, and observed the squirrels' responses. The data for the three age levels are shown in the table. If ground squirrels at different ages respond to the alarm signals in the same proportions, what would be the expected count for 6- to 15-day-old squirrels that freeze?

answer

C. ((40)(49)/98)

question

A study was conducted to investigate whether there are regional differences in peanut butter preference in the United States. The country was divided into 7 geographic regions, and in each region a random sample of peanut butter eaters were asked whether they preferred creamy or crunchy peanut butter. The responses were summarized in a 7-by-2 table of counts for each combination of geographic region and creamy or crunchy peanut butter preference. Which of the following tests is the most appropriate for the investigation?

answer

C. A chi-square test of homogeneity

question

The campus bookstore at a local university is interested in finding out whether the textbook preference and the class level (freshman, sophomore, junior, senior) of the student are associated. A random sample of 100 students is obtained, and each student in the sample is asked which textbook he or she prefers: new books, used books, or digital books. The students are also asked whether their class level is freshman, sophomore, junior, or senior. Which of the following is the appropriate test for the investigation?

answer

E. A chi-square test of independence

question

A random sample of 300 United States cell phone users were asked their age and the question "Do you regularly use your cell phone to text while eating dinner?" The number responding yes was tabulated separately for young adults (aged 18-29), older adults (aged 30-64), and elderly adults (aged 65 or older). The results are summarized in the following table. Which of the following would be the appropriate hypotheses to investigate whether the survey provides convincing statistical evidence that there is an association between a person's age-group and regular use of a cell phone to text while eating dinner?

answer

B. H0 :H0 : Among adults in the United States population, there is no association between age-group and cell phone usage to text while eating dinner.
Ha:Ha: Among adults in the United States population, there is an association between age-group and cell phone usage to text while eating dinner.

question

As a first step in developing a new drug to treat cancer in humans, an initial study of the drug is undertaken in rats. Three hundred rats with cancer are studied, and each is assigned to one of three treatments. One hundred rats are randomly assigned to a high dose of the new drug, 100 are randomly assigned to a low dose, and 100 are randomly assigned to a control group (no drug). After six months, each rat is examined and classified as having developed no tumors, one tumor, or two or more tumors.
Which of the following would be an appropriate alternative hypothesis in this study for a chi-square test for homogeneity of tumor response across treatments?

answer

B. Ha :Ha : There is a difference in the distribution of tumor status across the three treatments.

question

Data was collected from a simple random sample of 200 cell phone users age 18 or older in the United States. Each user was categorized by age-group and by whether he or she uses a certain cell phone app. The table shown summarizes the data, with expected cell counts in parentheses. Which statement is true about whether the conditions for a chi-square test for independence have been met?

answer

E. Not all of the expected cell counts are large enough to satisfy the conditions for the chi-square test for independence.

question

A manufacturing company with 350 employees is changing the employee health insurance plan to either plan A or plan B. The company wants to know if employees have a preference between the two plans and whether or not preference differs between those employees who have family members covered under the current plan (group 1) and those who do not (group 2). The human resources office takes a simple random sample from each of the two groups, sends information about both plans to the employees in each sample, and asks them whether they prefer plan A or plan B. The table summarizes the responses received, with expected cell counts in parentheses. Which statement is true about whether the conditions for the chi-square test for homogeneity have been met?

answer

D. The total sample size is too large to apply the chi-square test for homogeneity.

question

The national society of acupuncturists asked a random sample of 450 adults their opinion about acupuncture being a reasonable form of medicine or not a reasonable form of medicine. The table below shows the responses, along with the highest level of education achieved for each person selected. Assuming that all conditions for inference have been met, which of the following represents the correct chi-square test statistic and number of degrees of freedom to test whether there is an association between level of education and opinion about acupuncture?

answer

B. Ο2=(100β85.33)285.33+(80β80)280+(60β74.67)274.67+(60β74.67)274.67+(70β70)270+(80β65.33)265.33 with 2 degrees of freedom

question

A state political analyst wanted to see whether there is an association between the region where a person lives and whether the person is in favor of increasing the state gas tax. A random sample of 270 state residents was selected, and the table below shows the results of the survey. Which of the following is closest to the p-value of the appropriate test to investigate whether there is an association between the region where a person lives and whether the person is in favor of increasing the state gas tax?

answer

A. 0.0644

question

A chi-square test of independence was conducted to investigate whether there is an association between the location where a person lives in a city (north, south, east, or west) and who the person planned to vote for in the upcoming mayoral election (the incumbent or the challenger). A random sample of 100 potential voters was selected, and the hypothesis test had a chi-square test statistic of Ο2=9.84 with a p-value of 0.02. Which of the following statements is the correct interpretation of the p-value in context?

answer

E. Assuming that the location of where a person lives and who that person plans to vote for are independent, there is a 2 percent chance of finding a test statistic that is 9.84 or greater.

question

A hypothesis test was conducted to see whether there is an association between a person's income level and his or her education level. A random sample of 225 people was selected, and the appropriate hypothesis test was conducted. The chi-square test statistic and corresponding p-value were approximately 13.36 and 0.01, respectively. Which of the following is the correct interpretation of the p-value in the context of the test?

answer

A. Assuming that a person's income level and education level are independent, there is a 1 percent chance of finding a test statistic of 13.36 or greater.

question

A political analyst wanted to see whether there is an association between political affiliation and where a person lives. The analyst took a random sample of 1,250 people in a state and asked them which political party they were affiliated with and what county they lived in. The following are the hypotheses the analyst tested.
H0 : There is no association between party affiliation and the county in which a person lives.
Ha : There is an association between party affiliation and the county in which a person lives.
The chi-square test statistic and p-value of the hypothesis test were 19.78 and 0.003 respectively. Which of the following conclusions should be made about political affiliation and where a person lives?

answer

B. There is convincing statistical evidence to suggest that political affiliation and where a person lives are dependent.

question

A college administrator wanted to know if the proportion of students who request online classes, lab classes, or lecture classes was different at two different campuses. At each campus, the administrator took a random sample of 250 students and asked each student which type of class they preferred. The conditions for the appropriate test were verified, and the chi-square test statistic for the test was calculated to be 4.01 with an associated p-value of 0.1347. If the significance level of the test was Ξ±=.05, what conclusion should the college administrator make about the proportion of students who request online classes, lab classes, or lecture classes at two different campuses?

answer

D. There is not convincing statistical evidence to suggest that the proportion of students who request certain classes is different at each campus.