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1. Assume that a sample is used to estimate a population mean μ. Find the 98% confidence interval for a sample of size 401 with a
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2. Suppose we are interested in studying a population to estimate its mean. The population is normal and has a standard deviation
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3. A pollster wants to construct an 98% confidence interval for the proportion of adults who believe that economic conditions are
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4. A pollster wants to construct an 80% confidence interval for the proportion of adults who believe that economic conditions are
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5. sample of size n=38 has sample mean x=58 and sample standard deviation s=7.6. (a) Construct a 99% confidence interval for the
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6. Boxes of cereal are labeled as containing 14 ounces. Following are the weights, in ounces, of a sample of 16 boxes. It is
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7. Find the critical value Zva/2 needed to construct a confidence interval with level 96%.Round the answer to two decimal places.
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8. Out of 100 people sampled, 70 had kids. Based on this, construct a 99% confidence interval for the true population proportion of
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9. You intend to estimate a population mean with a confidence interval. You believe the population to have a normal distribution.
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10. Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 46
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11. Express the confidence interval 368.8 < mu < 678.8 in the form of bar(x) pm ME__________________ __________________
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12. Express the confidence interval (284.5,497.3) in the form of x-bar bar(x) pm ME
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13. You intend to estimate a population mean with a confidence interval. You believe the population to have a normal distribution.
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14. You measure 37 watermelons' weights, and find they have a mean weight of 57 ounces. Assume the population standard deviation is
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15. You intend to estimate a population mean with a confidence interval. You believe the population to have a normal distribution.
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16. A delivery company is logging the number of miles each employee drives each day. The company found an average of about 85.6
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17. In a random sample of 100 residents from a certain area it follows that 35 were in favour of the construction of a nuclear power
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18. Light bulbs supplied by a certain company have a length life that is approximately normally distributed, with the standard
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    2. 37 views
19. A hospital administrator intends to improve the level of emergency-room service by increasing support personnel. To justify the
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20. In a random sample of 100 residents from a certain area it follows that 35 were in favour of the construction of a nuclear power
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21. The heights of a random sample of 50 Hereford calves at birth showed a mean of 71 cm and a standard deviation of 6.7 cm.
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22. A random sample of 8 cigarettes of a certain brand has an average nicotine content of 2.6 milligram and standard deviation of
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23. The heights of a random sample of 50 Hereford calves at birth showed a mean of 71 cm and a standard deviation of 6.7 cm.
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24. In a random sample of 100 residents from a certain area it follows that 35 were in favour of the construction of a nuclear power
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    2. 29 views
25. / The masses of 6 containers of Chow dog food are:9.8 10.4 9.8 10 10.2 9.6 Find a 95% confidence interval for the mean mass of
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26. A ramdom sample of 150 workers showed that 90 workers are satisfied with the new medical scheme. Find a 90% confidence interval
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27. True or False: The difference between the lower limit of a confidence interval and the point estimate used in constructing the
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28. Given the population standard deviation is known as R500. A random sample of 50 individuals resulted in a mean of R10000. What
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29. True or False: A sample size of 36 provides a sample mean of 10. If the population variance is known to be 16 and the population
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30. True or False: The confidence interval for the mean will be wider for 95% confidence than for 90% confidence when all the other
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31. A quality control engineer is interested in the mean length of sheet insulation being cut automatically by machine. The desired
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32. A quality control engineer is interested in the mean length of sheet insulation being cut automatically by machine. The desired
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33. True or False: A sample size of 36 provides a sample mean of 10. If the population variance is known to be 16 and the population
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34. From a sample of 64 motorists working in Cape Town, the sample average time that it takes them to drive to work is 36 minutes.
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35. Suppose a 95% confidence interval for the population mean turns out to be (1 ; 2.1). To make more useful inferences from the
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36. True or False: A sample size of 36 provides a sample mean of 10. If the population variance is known to be 16 and the population
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37. . A random sample of 150 workers showed that 100 are satisfied with their new medical scheme. Construct a 90% confidence
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38. 1. The masses of 6 containers of Chow dog food are:9.5 10.4 9 11 10.5 9.6 Find a 95% confidence interval for the mean mass of
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39. The mean mass of 50 male students who showed above average participation in athletics was 68.2 kg with a standard deviation of 3
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40. In a random sample 500 people eating lunch at a cafeteria on various Fridays, it was found that 160 preferred seafood. Find a
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41. Two independent samples from populations that are normally distributed produced the following statistics: for sample 1 the
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42. 6. A hotel chain wants to estimate the mean number of rooms rented daily in a given month. The population of rooms rented daily
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43. An economist is interested in studying the incomes of consumers in a particular country. The population standard deviation is
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44. . A random sample of 9 cigarettes has an average nicotine content of 2.5 milligram with a standard deviation of 0.8 milligram.
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45. 7. The president of a university would like to estimate the proportion of the student population that owns a personal computer.
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46. Light bulbs supplied by a certain company have a length life that is approximately normally distributed, with the standard
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47. 7. The president of a university would like to estimate the proportion of the student population that owns a personal computer.
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    2. 30 views
48. A quality control engineer is interested in the mean length of sheet insulation being cut automatically by machine. The desired
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    2. 28 views
49. A random sample of 144 patients at a local clinic who had cataracts removed during the past year showed an average age of 60
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50. True or False: The confidence interval for the mean will be wider for 95% confidence than for 90% confidence when all the other
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51. True or False: A sample size of 36 provides a sample mean of 10. If the population variance is known to be 16 and the population
    1. 1 answer
    2. 28 views
52. From a sample of 64 motorists working in Cape Town, the sample average time that it takes them to drive to work is 36 minutes.
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    2. 25 views
53. True or False: The difference between the upper limit of a confidence interval and the point estimate used in constructing the
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54. A random sample of 144 patients at a local clinic who had cataracts removed during the past year showed an average age of 60
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55. True or False: The margin of error equals half the width of a confidence interval.
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56. True or False: The confidence interval estimate of the population mean is constructed around the sample mean.
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57. True or False: By increasing the level of confidence in a confidence interval, and you hold the sample size fixed, the
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58. A tyre manufacturer found that the sample mean tread life of 16 radial tyres tested was 60000 km with standard deviation 12000
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59. A tyre manufacturer found that the sample mean tread life of 49 radial tyres tested was 52345 km with standard deviation 12943
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60. From a sample of 100 Bloemfontein car commuters, the sample mean time to commute to work daily was found to be 35.8 minutes. It
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61. From a sample of 100 Bloemfontein car commuters, the sample mean time to commute to work daily was found to be 35.8 minutes. It
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62. From a sample of 100 Bloemfontein car commuters, the sample mean time to commute to work daily was found to be 35.8 minutes. It
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63. A standard flammability test for fabric is to place a standard-sized piece of fabric under a flame for a fixed period of time,
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64. A market research company wishes to know how many energy drinks teenagers drink each week. They want to construct a 80%confidenc
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65. A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective.Step 2 of 2 :
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66. Out of 167randomly selected adults in the United States who were surveyed, 88 exercise on a regular basis. Construct a 90%
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67. An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic.Step 2 of 2 :
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68. A survey of 71randomly selected homeowners finds that they spend a mean of $63 per month on home maintenance. Construct a 98%
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69. A research company desires to know the mean consumption of meat per week among people over age 43. They believe that the meat
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70. A professor wants to estimate how many hours per week her students study. A simple random sample of 73students had a mean of 15
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71. Given the following confidence interval for a population mean, compute the margin of error, E.10.18<μ<11.90
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72. A researcher wants to find a 90% confidence interval for the population proportion of those who support additional handgun
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73. Suppose a sample of size 400 yields p = 0.5 You'd like to construct a confidence interval with a margin of error only half as
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74. A researcher constructs a confidence interval for a population proportion using a sample of size 50. The value of p is.3, and
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75. A random sample of 250 men yielded 175 who said they'd ridden a motorcycle at some time in their lives, while a similar sample
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76. A random sample of 250 men yielded 175 who said they'd ridden a motorcycle at some time in their lives, while a similar sample
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77. Which of the following conditions must be met if you want to use z- procedures to construct a confidence interval for a
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78. QuestionA random sample of 187 adults was selected from a population of a town to determine their average savings account
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79. A random sample of 187 adults was selected from a population of a town to determine their average savings account balance. The
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80. A random sample of cell phones has a mean battery life of 715 minutes with a margin of error of 21 minutes. Interpret the
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81. A random sample of 25 office workers was selected to determine how much the average person spends weekly on groceries. The
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82. An advertiser claims that 9 out of 10 dentists (90%) recommend Brand X toothpaste. A consumer group investigates the truth of
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83. A college surveys a sample of 116 of its students to determine whether they would prefer a final exam or a final paper. Out of
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84. A researcher wants to create a confidence interval for the proportion of residents in a city who support a proposed bill. She
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85. A survey of 650 people reported that 32% favored the reelection of the current mayor. Which of the following correctly
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86. If the 99% confidence interval is given by (0.40,0.52) , which of the following correctly interprets the margin of error?(1
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87. If the interval for a sample proportion is (0.49,0.54) with 99% confidence, which of the following correctly calculates the
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88. If the 99% confidence interval is given by (0.40,0.52) , which of the following correctly interprets the margin of error?(1
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89. A survey was taken of 850 people in a neighborhood, and the results were that 230 people were planning on voting for a
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90. A doctor would like to know what proportion of their patients are vitamin D deficient. They choose a random sample of3 0
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91. A doctor would like to know what proportion of their patients are vitamin D deficient. They choose a random sample of 30
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92. What's the critical value of ( t ^ * ) needed to construct a 98% confidence interval for the mean of a distribution based on a
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93. As the desired confidence level increases, z increases and thus the confidence interval decreases.* 1 point True False
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94. ) Find 95% confidence limits for the mean of a normality distributed population from which the following sample was taken and
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    2. asked by Rajesh
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95. A random sample of size 81 whose variant is 26.25 and mean is 32 construct a 98% confidence interval
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    2. asked by Rajesh
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96. A random sample of size 81 whose variance is 26.25 and mean is 32. Construct a 98% confidence interval
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97. A random sample of size 81 was taken whose variance is 20.25 and means 32 construct 98% confidence limits
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98. A random sample of 400 items is found to have mean of 82 and S.D of 18.find 95% confidence Limits for the mean of the population
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99. Which of the following estimates at a 95% confidence level most likely comes from a small sample?48% (+ or - 21%) 59% (+ or -
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100. A sample of 64 was taken from a population, with the mean of the sample being 42 and the standard deviation of the sample being
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