# Statistics MCQs – Estimation Part 3

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41. Your statistics lecturer wants you to determine a confidence interval estimate for the mean test mark for the next test. In the past, the test marks have been normally distributed with a population standard deviation of 25.2. A 95 % confidence interval estimate if your class has 30 students and a sample mean mark of 74.2 is:

a. 63.14 to 85.26

b. 65.18 to 83.22

c. 65.63 to 82.77

d. 64.14 to 84.26

e. 68.14 to 80.26

Answer: B

42. Your statistics lecturer wants you to determine a confidence interval estimate for the mean test mark for the next test. In the past, the test marks have been normally distributed with a population standard deviation of 30.9. A 95 % confidence interval estimate if your class has 50 students and a sample mean mark of 74.2 is:

a. 63.14 to 85.26

b. 65.18 to 83.22

c. 65.63 to 82.77

d. 64.14 to 84.26

e. 68.14 to 80.26

Answer: C

43. Your statistics lecturer wants you to determine a confidence interval estimate for the mean test mark for the next test. In the past, the test marks have been normally distributed with a population standard deviation of 28.1. A 95 % confidence interval estimate if your class has 30 students and a sample mean mark of 74.2 is:

a. 63.14 to 85.26

b. 65.18 to 83.22

c. 65.63 to 82.77

d. 64.14 to 84.26

e. 68.14 to 80.26

Answer: D

44. Your statistics lecturer wants you to determine a confidence interval estimate for the mean test mark for the next test. In the past, the test marks have been normally distributed with a population standard deviation of 30.9. A 95 % confidence interval estimate if your class has 100 students is and a sample mean mark of 74.2:

a. 63.14 to 85.26

b. 65.18 to 83.22

c. 65.63 to 82.77

d. 64.14 to 84.26

e. 68.14 to 80.26

Answer: E

45. An economist is interested in studying the monthly incomes of consumers in a particular region. The population standard deviation of monthly income is known to be R1000. A random sample of 50 individuals resulted in an average monthly income of R15000. What is the upper end point in a 99 % confidence interval for the average monthly income in this region?

a. R15364

b. R15328

c. R15347

d. R15382

e. R15332

Answer: A

46. An economist is interested in studying the monthly incomes of consumers in a particular region. The population standard deviation of monthly income is known to be R900. A random sample of 50 individuals resulted in an average monthly income of R15000. What is the upper end point in a 99 % confidence interval for the average monthly income in this region?

a. R15364

b. R15328

c. R15347

d. R15382

e. R15332

Answer: B

47. An economist is interested in studying the monthly incomes of consumers in a particular region. The population standard deviation of monthly income is known to be R1000. A random sample of 55 individuals resulted in an average monthly income of R15000. What is the upper end point in a 99 % confidence interval for the average monthly income in this region?

a. R15364

b. R15328

c. R15347

d. R15382

e. R15332

Answer: C

48. An economist is interested in studying the monthly incomes of consumers in a particular region. The population standard deviation of monthly income is known to be R1050. A random sample of 50 individuals resulted in an average monthly income of R15000. What is the upper end point in a 99 % confidence interval for the average monthly income in this region?

a. R15364

b. R15328

c. R15347

d. R15382

e. R15332

Answer: D

49. An economist is interested in studying the monthly incomes of consumers in a particular region. The population standard deviation of monthly income is known to be R1000. A random sample of 60 individuals resulted in an average monthly income of R15000. What is the upper end point in a 99 % confidence interval for the average monthly income in this region?

a. R15364

b. R15328

c. R15347

d. R15382

e. R15332

Answer: E

50. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (177.22 cm; 179.18 cm) . What is the value of the sample mean for this sample?

a. 178.20cm

b. 179.24cm

c. 177.38cm

d. 178.42cm

e. 176.58cm

Answer: A

51. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (178.54 cm; 179.94 cm) . What is the value of the sample mean for this sample?

a. 178.20cm

b. 179.24cm

c. 177.38cm

d. 178.42cm

e. 176.58cm

Answer: B

52. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (176.50 cm; 178.26 cm) . What is the value of the sample mean for this sample?

a. 178.20cm

b. 179.24cm

c. 177.38cm

d. 178.42cm

e. 176.58cm

Answer: C

53. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (177.89 cm; 178.95 cm) . What is the value of the sample mean for this sample?

a. 178.20cm

b. 179.24cm

c. 177.38cm

d. 178.42cm

e. 176.58cm

Answer: D

54. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (175.90 cm; 177.25 cm) . What is the value of the sample mean for this sample?

a. 178.20cm

b. 179.24cm

c. 177.38cm

d. 178.42cm

e. 176.58cm

Answer: E

55. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (177.22 cm; 179.18 cm) . What is the value of the standard deviation of the population from which this sample was drawn?

a. 5.0

b. 3.6

c. 4.5

d. 2.7

e. 3.4

Answer: A

56. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (178.54 cm; 179.94 cm) . What is the value of the standard deviation of the population from which this sample was drawn?

a. 5.0

b. 3.6

c. 4.5

d. 2.7

e. 3.4

Answer: B

57. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (176.50 cm; 178.26 cm) . What is the value of the standard deviation of the population from which this sample was drawn?

a. 5.0

b. 3.6

c. 4.5

d. 2.7

e. 3.4

Answer: C

58. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (177.89 cm; 178.95 cm) . What is the value of the standard deviation of the population from which this sample was drawn?

a. 5.0

b. 3.6

c. 4.5

d. 2.7

e. 3.4

Answer: D

59. On the basis of a random sample of 100 men from a particular province in South Africa, a 95 % confidence interval for the mean height of men in the province is found to be (175.90 cm; 177.25 cm) . What is the value of the standard deviation of the population from which this sample was drawn?

a. 5.0

b. 3.6

c. 4.5

d. 2.7

e. 3.4

Answer: E

60. In developing a 95 % confidence interval estimate for a population mean, the interval estimate was (62.84; 69.46) . What was the sample mean?

a. 66.15

b. 65.83

c. 65.35

d. 67.01

e. 66.87

Answer: A