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- 1. Open EndedRachel scored 670 on the analytic portion of the GRE (Graduate Record Exam). GRE scores are Normally distributed with a mean of 600 and a standard deviation of 30. How many standard deviations is Rachel's score above the mean?
- 2. Open EndedFor -1.65 < z < 1.75, which one of the following graphs best represents the correct shaded area or proportion?
- 3. Open EndedUsing the Standard Normal Table, what proportion of observations on the standard Normal curve satisfy -1.65 < z < 1.75?
- 4. Open EndedUsing the Standard Normal Table, what is the z-score with 0.9345 to its left?
- 5. Open EndedHow many standard deviations above and below the mean do the quartiles of any Normal distribution lie? (Use the standard Normal distribution to find Q1 and Q3 for z-scores.)
- 6. Open EndedThe Weschler Adult Intelligence Scale (WAIS) is the most common "IQ" test. The scale of scores is approximately Normal with a mean of 100 and a standard deviation of 15. What proportion of adults have an IQ less than 90? (Draw and label the Normal curve and use the Standard Normal Table.)
- 7. Open EndedThe Weschler Adult Intelligence Scale (WAIS) is the most common "IQ" test. The scale of scores is approximately Normal with a mean of 100 and a standard deviation of 15. What is the probability that a randomly selected adult will have an IQ greater than 140?
- 8. Open EndedThe Weschler Adult Intelligence Scale (WAIS) is the most common "IQ" test. The scale of scores is approximately Normal with a mean of 100 and a standard deviation of 15. What is the probability that a randomly selected adult will have an IQ between 130 and 140?
- 9. Open EndedThe Weschler Adult Intelligence Scale (WAIS) is the most common "IQ" test. The scale of scores is approximately Normal with a mean of 100 and a standard deviation of 15. Above what value are 20% of all IQ scores?
- 10. Open EndedWhich of the following intervals corresponds to the smallest area under a Normal curve? Q1 to Q3 μ to μ + 3σ Q1 to μ + 2σ μ - σ to Q3
- 11. Open EndedWhich of the following is a parameter? The proportion of voters in a national sample of 1500 who say they will vote for the incumbent president The mean GPA of all incoming freshmen at a state university The standard deviation of the weights of a sample of National League Football players The median income of a sample of 300 university professors
- 12. Fill in the BlankThe sampling distribution of x̄ gives _______ from all possible samples of the same size from the same population.
- 13. Open EndedSuppose we take all possible samples of the same size from a population and for each sample, we compute x̄. Will the mean of these x̄ values will be exactly equal to the mean of the population (μ) from which the samples were taken?
- 14. Open EndedSuppose we take all possible samples of the same size from a population and for each, we compute x̄. Will the standard deviation of these x̄ values will be less than or equal to the standard deviation of the population from which the samples were taken?
- 15. Open EndedAccording to the Central Limit Theorem, for random samples, what is the approximate shape of the sampling distribution of x̄ when the population distribution is non-Normal?
- 16. Open EndedSuppose we have a very right skewed population distribution where μ = 80 and σ = 20. For random samples of size n = 100, what is the mean of the sampling distribution of x̄?
- 17. Open EndedSuppose we have a very right skewed population distribution where μ = 80 and σ = 20. For random samples of size n = 100, what is the standard deviation of the sampling distribution of x̄?
- 18. Open EndedSuppose we have a very right skewed population distribution where μ = 80 and σ = 20. For random samples of size n = 100, what is the shape of the sampling distribution of x̄?
- 19. Open EndedFor small random samples from a Normal population distribution, the shape of the sampling distribution of x̄ is...
- 20. Open EndedWhat is the advantage of reporting the average of several measurements rather than the result of a single measurement?
- 21. Open EndedWhat is the purpose of a statistical control chart?
- 22. Open EndedA manufacturing process produces bags of cookies. The weights of these bags are known to be Normally distributed and should have a mean of μ = 15.0 ounces with a standard deviation of σ = 0.4 ounces. In order to monitor the process, four bags are selected periodically and their average weight (x̄) is computed. What is the parameter of interest?
- 23. Open EndedA manufacturing process produces bags of cookies. The weights of these bags are known to be Normally distributed and should have a mean of μ = 15.0 ounces with a standard deviation of σ = 0.4 ounces. In order to monitor the process, four bags are selected periodically and their average weight (x̄) is computed. In order to construct an x̄-chart for this process, what number should be used as the center line?
- 24. Open EndedA manufacturing process produces bags of cookies. The weights of these bags are known to be Normally distributed and should have a mean of μ = 15.0 ounces with a standard deviation of σ = 0.4 ounces. In order to monitor the process, four bags are selected periodically and their average weight (x̄) is computed. What is the upper limit of the control chart for this process?
- 25. Open EndedA manufacturing process produces bags of cookies. The weights of these bags are known to be Normally distributed and should have a mean of μ = 15.0 ounces with a standard deviation of σ = 0.4 ounces. In order to monitor the process, four bags are selected periodically and their average weight (x̄) is computed. What is the lower limit of the control chart for this process?
- 26. Open EndedWhat is the symbol for the sample mean?
- 27. Open EndedWhat is the symbol for standard deviation?
- 28. Open EndedWhat do we use to estimate μ?
- 29. Open EndedAn administrator in a very large company wants to estimate the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars. Historically, nitrogen oxide levels have been known to be Normally distributed with a standard deviation of 0.15 g/ml. What is the parameter of interest that the administrator wants to estimate?
- 30. Open EndedAn administrator in a very large company wants to estimate the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars. Historically, nitrogen oxide levels have been known to be Normally distributed with a standard deviation of 0.15 g/ml. What statistic is used to estimate the parameter of interest?
- 31. Open EndedCan statistical inference can be defined as making generalizations about the population based on sample data.
- 32. Open EndedA study of child preferences for milk chocolate was performed. Based on sample results, researchers were 95% confident that the proportion of children that liked milk chocolate was between 0.75 and 0.93. What type of inference is being used?
- 33. Open EndedBased on sample results, researchers estimate that μ, the mean height of all female students in a university, is 64 inches. What type of inference is being used?
- 34. Open EndedIs point estimation is a form of statistical inference in which, based on the sample data, we estimate the unknown parameter of interest using a range of plausible values?
- 35. Open EndedA recent study claimed that half of all college students "drink to get drunk" at least once in a while. Believing that the true proportion is much lower, the College Alcohol Study interviews an SRS of 14,941 college students about their drinking habits and finds that 7,352 of them occasionally "drink to get drunk". What type of statistical inference is this?
- 36. Open EndedWhat is the t* associated with 98% confidence and df = 37?
- 37. Fill in the BlankIn confidence interval estimation, we use a confidence interval to estimate ________
- 38. Open EndedAn administrator in a very large company wants to estimate the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars. Historically, nitrogen oxide levels have been known to be Normally distributed. A 98% confidence interval estimate for the mean nitrogen oxide level was computed. What do we hope to find in this confidence interval?
- 39. Open EndedAn administrator in a very large company wants to estimate the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars. Historically, nitrogen oxide levels have been known to be Normally distributed. The correct computation of the 98% confidence interval estimate is (0.87 g/ml, 0.97 g/ml). Which of the following is a correct interpretation of this 98% confidence interval?
- 40. Fill in the BlankThe t-distribution with 6 degrees of freedom has _____ than the standard normal distribution
- 41. Open EndedSuppose the 95% confidence interval estimate for the mean monthly cost for Internet service for all Internet users is ($19.90, $21.90). Which of the following is a correct interpretation of this 95% confidence interval?
- 42. Open EndedThe purpose of a confidence interval is to provide...
- 43. Open EndedThe BYU Testing Center is known for being the location with the most prayers said per capita. Researchers asked a random sample of 47 BYU students to estimate the number of prayers they said in the BYU Testing Center last semester. The researchers are willing to consider these 47 BYU students as an SRS from the population of all BYU students. Researchers plan to use these data to estimate the mean number of prayers said by students last semester in the BYU Testing Center with 99% confidence. Suppose the confidence interval turned out to be (8.001, 13.829). What is an appropriate interpretation of this interval?
- 44. Open EndedThe weekly oral dosage of anabolic steroids was measured on a sample of 20 body builders. A 95% confidence interval estimate for the average weekly oral dose of anabolic steroids obtained from these results was 152 mg to 194 mg. Which one of the following is a correct interpretation of this confidence interval?
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