This quiz works best with JavaScript enabled. Home > Ugc Net > Paper 1 > Research Stats > Confidence Intervals – Quiz 1 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Confidence Intervals Quiz 1 (30 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. We plan to survey college seniors to see what proportion plan to attend grad school next year. Using 98% confidence, how many students should we survey if we wish the margin of error to be within 3%? A) Approximately 1500. B) Approximately 1050. C) Approximately 40. D) Approximately 1170. Show Answer Correct Answer: A) Approximately 1500. 2. A random sample of 42 textbooks has a mean price of $ 114.50 and a standard deviation of $ 12.30. Find a point estimate for the mean price of all textbooks. A) $ 2.73. B) $ 42. C) $ 114.50. D) $ 12.30. Show Answer Correct Answer: C) $ 114.50. 3. What is the format for interpreting a confidence interval? A) There is convincing evidence that C% gives the interval ( , ) capturing the parameter in question. B) The interval from to captures the true mean in context. C) C% of samples of the same size taken from the same population will capture the parameter in question. D) We are C% confident that the interval from to captures the [parameter in context]. Show Answer Correct Answer: D) We are C% confident that the interval from to captures the [parameter in context]. 4. What is the degrees of freedom equal to for the t distribution? A) N+1. B) N. C) 1-n. D) N-1. Show Answer Correct Answer: D) N-1. 5. What can you do to reduce the margin of error? A) Decrease sample size. B) Decrease the confidence level. C) Increase the confidence level. D) Increase sample size. Show Answer Correct Answer: D) Increase sample size. 6. In a survey of 104 students, it was found that 79 went to the homecoming game this year. Calculate a 99% confidence interval for p. A) (0.691, 0.829). B) (0.652, 0.868). C) (0.678, 0.842(. D) (0.685, 0.895). Show Answer Correct Answer: B) (0.652, 0.868). 7. Margin of Error is equal to: A) Standard Deviation. B) 2 * Standard Deviation. C) Critical Value. D) Point Estimate. Show Answer Correct Answer: B) 2 * Standard Deviation. 8. Construct a 95% confidence interval for the population mean, $\mu$. Assume the population has a normaldistribution. A sample of 20 college students had mean annual earnings of $ 3120 with a standard deviation of$ 677. A) ($ 2135, $ 2567). B) ($ 1324, $ 1567). C) ($ 2657, $ 2891). D) ($ 2803, $ 3437). Show Answer Correct Answer: D) ($ 2803, $ 3437). 9. Choose the appropriate confidence interval for the situation:A random sample of 75 oak trees has a mean height of 62 ft. Assume a population standard deviation of 3.8 ft. A) Z confidence interval for a mean. B) Z confidence interval for a proportion. C) T confidence interval for a mean. D) T confidence interval for a proportion. Show Answer Correct Answer: A) Z confidence interval for a mean. 10. Choose the appropriate confidence interval for the situation:A random sample of 30 movie theaters showed that the average price for a movie was $ 10 with a standard deviation of $ 1.20. A) Z confidence interval for a mean. B) T confidence interval for a mean. C) T confidence interval for a proportion. D) Z confidence interval for a proportion. Show Answer Correct Answer: B) T confidence interval for a mean. 11. In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $ 1800 and a sample standard deviation of $ 950. Construct a 99% confidence interval for the repair cost. A) (1069.77, 2530.23). B) (1077.13, 2522.87). C) (1167.15, 2432.85). D) None of these. Show Answer Correct Answer: A) (1069.77, 2530.23). 12. A 90% confidence interval for the mean speed driven by cars on Due West Road is given by (21, 45). What was the margin of error of this study? A) 12. B) 24. C) 33. D) None of these. Show Answer Correct Answer: A) 12. 13. The height of women is normally distributed with an average height of 64 inches and a standard deviation of 2.5 inches. What interval contains 99.7% of all data? A) 56.5 to 71.5. B) 61.5 to 66.5. C) 59 to 69. D) 2.5 to 99.7. Show Answer Correct Answer: A) 56.5 to 71.5. 14. Determine the minimum sample size needed to construct a 95% confidence interval for the mean age of employees at a company. The estimate must be accurate to within 0.5 year. Assume the standard deviation is 4.8 years. A) 354. B) 355. C) 18. D) 19. Show Answer Correct Answer: B) 355. 15. Which of the following is the definition of a "point estimate?" A) The confidence interval. B) The average of a sample. C) The midpoint of a confidence interval. D) The average of a population. Show Answer Correct Answer: C) The midpoint of a confidence interval. 16. A sample of 30 women finds the mean height to be 62.3 in and the standard deviation to be 1.5 in. Find the margin of error of women's heights with 95% confidence. A) 1.699. B) 0.537. C) 0.56. D) 19.325. Show Answer Correct Answer: C) 0.56. 17. Compute a 90% confidence interval for the situation:A random sample of 30 movie theaters showed that the average price for a movie was $ 10 with a standard deviation of $ 1.20. A) (9.628, 10.372). B) (9.71, 10.29). C) (9.934, 10.066). D) (9.64, 10.36). Show Answer Correct Answer: A) (9.628, 10.372). 18. A random sample of 100 WHS students found that 53 of them were in possession of a pencil. What is the p-hat for this sample? A) 0.53. B) 0.5. C) 0.47. D) 1. Show Answer Correct Answer: A) 0.53. 19. Thirty randomly selected students took the calculus final. If the sample mean was 92 and the standard deviation was 9.4, construct a 99 percent confidence interval for the mean score of all students from which the sample was gathered. A) 87.77 < $\mu$ < 96.23. B) 89.08 < $\mu$ < 94.92. C) 87.27 < $\mu$ < 96.73. D) 87.29 < $\mu$ < 96.71. Show Answer Correct Answer: C) 87.27 < $\mu$ < 96.73. 20. Which of the following values below represents the critical value for a 98% confidence interval? A) 2.326. B) 1.645. C) 2.054. D) 3.091. Show Answer Correct Answer: A) 2.326. 21. Which confidence would result in a wider interval (assuming nothing else changed), 91% or 97%? A) 97%, z* is larger for higher confidence intervals. B) 97%, the standard error is larger for higher confidence intervals. C) 91%, z* is larger for lower confidence intervals. D) 91%, the standard error is smaller for lower confidence intervals. Show Answer Correct Answer: A) 97%, z* is larger for higher confidence intervals. 22. A random sample of 100 visitors to a popular theme park spent an average of $ 142 on the trip with a standard deviation of $ 47.5. Which of the following would be the 98% confidence interval for the mean money spent by all visitors to this theme park? A) ($ 130.77, $ 153.23). B) ($ 132.69, $ 151.31). C) ($ 140.88, $ 143.12). D) ($ 132.77, $ 151.43). Show Answer Correct Answer: A) ($ 130.77, $ 153.23). 23. A sample of 400 racing cars showed that 80 cars cost over $ 700, 000. What is the 99% confidence interval of the true proportion of cars costing over $ 700, 000? A) 0.148 < p < 0.252. B) 0.023 < p < 0.045. C) 0.001 < p < 0.005. D) 0.566 < p < 0.693. Show Answer Correct Answer: A) 0.148 < p < 0.252. 24. Compute a 98% confidence interval:Last year, the times for Midlo soccer games were normally distributed with a standard deviation of 2.8 minutes. A random sample of 7 soccer games this year had an average length of 94 minutes. A) (91.827, 96.173). B) (91.235, 96.765). C) (91.538, 96.462). D) (90.674, 97.326). Show Answer Correct Answer: C) (91.538, 96.462). 25. Complete the equation:point estimate +/ ..... A) Standard deviation. B) Margin of error. C) Critical value. D) Confidence level. Show Answer Correct Answer: B) Margin of error. 26. A newspaper reporter asked an SRS of 100 residentsin a large city for their opinion about the mayor'sjob performance. Using the results from the sample, the C% confidence interval for the proportion of allresidents in the city who approve of the mayor's jobperformance is 0.565 to 0.695. What is the value of C? A) 90. B) 82. C) 95. D) 86. Show Answer Correct Answer: B) 82. 27. Thirty-five randomly selected students took the calculus final. If the sample mean was 92 and the standard deviation was 9.4, construct a 90 percent confidence interval for the mean score of all students. A) 89.39 < $\mu$ < 94.61. B) 87.29 < $\mu$ < 96.71. C) 89.08 < $\mu$ < 94.92. D) 87.77 < $\mu$ < 96.23. Show Answer Correct Answer: A) 89.39 < $\mu$ < 94.61. 28. A random sample of 85 sixth-graders in a large city take a course designed to improve scores on a reading comprehension test. Based on this sample, a 90% confidence interval for the mean improvement in test scores for all sixth-graders in the city taking this course is found to be (12.6, 14.8). Which of the following are the sample mean and margin of error on which this interval is based? A) Sample Mean = 13.7; Margin of Error = 1.1. B) Sample mean = 13.7; Margin of Error = 2.2. C) Sample mean is unknown; Margin of Error = 2.2. D) None of above. Show Answer Correct Answer: A) Sample Mean = 13.7; Margin of Error = 1.1. 29. A study found that in a sample of 44 subjects, 9 of agree that children under 6 shouldn't be taken to nice restaurants. Calculate a 95% confidence interval for p. A) (0.117, 0.292). B) (0.048, 0.361). C) (0.082, 0.318). D) (0.105, 0.305). Show Answer Correct Answer: C) (0.082, 0.318). 30. If random samples are selected from a population, what happens to the margin of error is the sample size is increased from 50 to 200? A) It decreases. B) It increases. C) There is no way to know without more information. D) It remains the same. Show Answer Correct Answer: A) It decreases. Next →Related QuizzesPaper 1 QuizzesUgc Net QuizzesConfidence Intervals Quiz 2Confidence Intervals Quiz 3Confidence Intervals Quiz 4Analysis Of Variance QuizChi Square QuizCoefficient Of Variation Discrete Serious And Continuous Serious QuizConcept Of Point And Interval Estimation QuizConcept Of Sampling And Other Concepts Related To Sampling Quiz 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books