 STAT 100 STAT100 Final Exam Answers - PSU

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STAT 100 Final Exam (Penn State University)

1. Since the nature of the population does not matter, the sampling distribution of a sample proportion will approximately follow the normal distribution, even for a convenience sample. Since the nature of the population does not matter, the sampling distribution of a sample proportion will approximately follow the normal distribution, even for a convenience sample.
2. If a statistical hypothesis test turns out to be significant, then it is not possible to make a type 2 error.
3. Everything else being equal, a confidence interval for an average will be shorter if the sample size is much larger.
4. For all of the books in the Library of Congress, the correlation between the thickness of the books (in inches) and their number of pages would be positive.
5. If a person feels better after taking a placebo, the pain was not real.
6. The average of 10 independent measurements will be more reliable than a single measurement made by the same instrument.
7. When you flip a thumbtack into the air, it can land point up or point down. True or False: Since there are just two possibilities, the chance of each one must be 50%.
8. A p-value is the probability that the null hypothesis is correct.
9. The weights of pallets of red bricks in a warehouse average 1150 pounds with a standard deviation of 25 pounds and follow the normal distribution quite closely. What percentage of the pallets weigh between 1145 and 1155 pounds?
10. When a die is rolled there is a one out of six (0.167) chance that it lands on a “one”. Which is most likely?
11. A random sample of 100 college students found that they got an average of 6 hours sleep the night before their last midterm with a standard deviation of 2 hours. This says that a 95% confidence interval for average hours of sleep for all students before a midterm is:
12. An accountant believes that the average amount spent by customers at an online florist will be higher than the current \$50 if free shipping is offered. To test the null hypothesis of μ = 50 versus the alternative of μ > 50 the accountant conducts a study using a large random sample and finds a test statistic of z = -0.05. The p-value for this test would be
13. The director of admissions in a small college administered a newly designed entrance test to 100 students selected at random from the upcoming freshman class. The purpose of this study was to determine whether students' grade point average (GPA) at the end of the freshman year can be predicted from the entrance test score. At the end of the year when all the data are available, what would be the graph you should use to display the data?
14. By using a smaller sample size in an experiment, a researcher risks:
15. Boxplots of the heights (in inches) of the male (m) and female (f) students in a statistics class are shown in the figure below
16. In a survey of military veterans, the variable “branch of service” (army, navy, marines, coast guard, etc.) is
17. A random sample of 1,000 residents of Montana (population 1 million) is taken to estimated the percentage of adults in that state who do not have cell phone service. A similar survey of 1000 adult residents is conducted using the same methodology in California (population 39 million). Comparing the two polls we would find that
18. A linear regression is used to make predictions for the sale price of a house (\$) using the appraised value (\$) of the land it sits on as the explanatory variable. The slope of that line would indicate:
19. In one city, 30 percent of the households have at least three devices that can be used to browse the internet, while 35 percent have one internet capable device and 15% have no devices that can be used to browse the internet. A household is randomly selected from the city. The chance that it has exactly two internet capable devices is:
20. A researcher would like to study how guns that are used in crimes are obtained. To do this, he proposes interviewing inmates who have been convicted of crimes involving the use of a gun. This would not be appropriate under Human subjects rules because
21. The average amount spent by a lunch customer at a sandwich shop is \$6. Which is more likely?
22. If you select a college student at random then whether they are engineering majors and whether they are female are
23. A researcher wants to find out what genes in the body are associated with surviving the ebola virus. Blood samples are taken from twenty people who contracted ebola but survived and from twenty others who dies from the disease. A microarray is used to test 10,000 different genes simultaneously to see which ones had significantly elevated RNA expression compared in the survivors versus those that died (i.e. a different significance test is planned for each individual gene). The problem with this is
24. Correlations will give a deceiving impression of the strength of an association
25. Above is a histogram of the pulse rates (heart beats per minute) for a group of students. One student had a pulse rate of 62 beats per minute. You can tell from the histogram that
26. Thirty percent (30%) of the cell phones in King County Washington use Sprint for their wireless service. If a random sample of 25 people with cell phones is selected in that county, then the percentage of them with Sprint service will be around 30% give or take a standard deviation of
27. The mayor of Los Angeles wants to sample the opinions of the adult residents of the city in order to estimate the percentage who favor the mayor’s proposal to tighten restrictions on public smoking. Nine hundred people are chosen at random from the Los Angeles phone directory, and 60% of them favor the mayor’s proposal. What is the population and the parameter in this situation
28. A common measurement of the lifetime smoking habits of subjects in observational studies dealing with heart disease is the number called “Pack Years.” This number is computed as: (lifetime average number of packs smoked per day) x (number of years smoked)
29. When the P-value is 0.5,
30. In this situation what is the null and alternative hypotheses?
31. To measure the amount of variability in the average mileage under the null hypothesis, we can use:
32. The conclusion from this significance test of the hypotheses in question #31 is
33. A confidence interval for the true average mpg of this model car:
34. Use the information below to answer the questions that follow:
35. What are the explanatory and response variables in this study?
36. This research is:
37. The researcher said that the results were statistically significant. Does this mean the results show a strong effect?
38. The value of 8% is:
39. The evidence presented would be stronger if
40. Use the information below to answer the questions that follow:
41. The standard error for the average amount of time that the lithium polymer battery will last before recharging is
42. A 95% confidence interval for the average amount of time that the lithium ion battery will last before recharging is
43. A 95% confidence interval for the difference in battery life between the two types is:
44. If we had made an 80% confidence interval in problem #42 then:

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