Question 1

A sample standard deviation is the best point estimate of the

Accepted Answer

A)  population range 
B)  population skewness 
C)  population mode 
D)  population standard deviation 
E)  population variance 
A)  population range 
B)  population skewness 
C)  population mode 
D)  population standard deviation 
E)  population variance D

Question 2

The following summarizes the average price of Air Canada stock at the end of 20 randomly selected weeks in 2000.

Accepted Answer

A)  [9467.57, 10 084.68] 
B)  [9401.76, 10 150.50] 
C)  [9628.70, 9923.55] 
D)  [9468.61, 10 083.65] 
E)  Unable to determine from the information given 
A)  [9467.57, 10 084.68] 
B)  [9401.76, 10 150.50] 
C)  [9628.70, 9923.55] 
D)  [9468.61, 10 083.65] 
E)  Unable to determine from the information given A

Question 3

A sample of 20 is selected from the population. What is the number of degrees of freedom used to determine the appropriate critical t-value?

Accepted Answer

A)  20 
B)  19 
C)  21 
D)  25 
E)  None of the choices are correct 
A)  20 
B)  19 
C)  21 
D)  25 
E)  None of the choices are correct B

Question 4

A 95% confidence interval infers that the population mean

Accepted Answer

A)  is between 0 and 100% 
B)  is within ± 1.96 standard deviations of the sample mean 
C)  is within ± 1.96 standard errors of the sample mean 
D)  is within ± 1.645 standard deviations of the sample mean 
E)  is too large 
A)  is between 0 and 100% 
B)  is within ± 1.96 standard deviations of the sample mean 
C)  is within ± 1.96 standard errors of the sample mean 
D)  is within ± 1.645 standard deviations of the sample mean 
E)  is too large

Question 5

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. Develop a 95% confidence interval for the mean annual consumption of sugar.

Accepted Answer

A)  23.06 to 30.94 
B)  22.20 to 31.80 
C)  20.37 to 33.63 
D)  23.30 to 30.70 
E)  23.0 to 30.0 
A)  23.06 to 30.94 
B)  22.20 to 31.80 
C)  20.37 to 33.63 
D)  23.30 to 30.70 
E)  23.0 to 30.0

Question 6

i. The 95 percent confidence interval states that 95 percent of the sample means of a specified sample size selected from a population will lie within plus and minus 1.96 standard deviations of the hypothesized population mean.
Ii) A distribution of sample means is normally distributed with a mean equal to the population mean and a standard deviation equal to the standard error of the mean.
Iii) A sample mean is the best point estimate of a population mean.

Accepted Answer

A)  (i), (ii) and (iii) are all correct statements 
B)  (i) and (ii) are correct statements, but not (iii). 
C)  (i) and (iii) are correct statements but not (ii). 
D)  (ii) and (iii) are correct statements but not (i). 
E)  All statements are false 
A)  (i), (ii) and (iii) are all correct statements 
B)  (i) and (ii) are correct statements, but not (iii). 
C)  (i) and (iii) are correct statements but not (ii). 
D)  (ii) and (iii) are correct statements but not (i). 
E)  All statements are false

Question 7

A survey of 144 retail stores revealed that the average price of a DVD was $375 with a standard error of $20. What is the 95% confidence interval to estimate the true cost of the DVD?

Accepted Answer

A)  $323.40 to $426.60 
B)  $328.40 to $421.60 
C)  $335.00 to $415.00 
D)  $335.80 to $414.20 
E)  None of the choices are correct 
A)  $323.40 to $426.60 
B)  $328.40 to $421.60 
C)  $335.00 to $415.00 
D)  $335.80 to $414.20 
E)  None of the choices are correct

Question 8

A statistics professor wishes to estimate the average mark on a term test for a course that has multiple sections and many students. A survey of some of the students registered for the course reveals the following results:   The student from the course wonders whether the population mean could have been 75 or 80.

Accepted Answer

A)  Since 80 is within the 95% confidence interval, the population mean is likely to be 80. 
B)  Since 80 is not within the 95% confidence interval, the population mean is not likely to be 80. 
C)  Since 75 is within the 95% confidence interval, the population mean is likely to be 75. 
D)  Since neither 75 nor 80 is within the 95% confidence interval, the population mean is not likely to be 75 or 80. 
E)  B & C are true 
A)  Since 80 is within the 95% confidence interval, the population mean is likely to be 80. 
B)  Since 80 is not within the 95% confidence interval, the population mean is not likely to be 80. 
C)  Since 75 is within the 95% confidence interval, the population mean is likely to be 75. 
D)  Since neither 75 nor 80 is within the 95% confidence interval, the population mean is not likely to be 75 or 80. 
E)  B & C are true

Question 9

Reasoning from a sample or small group to the entire group or population is called_________

Accepted Answer

statistica

Question 10

A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spent studying per week. Assuming a standard deviation of 6 hours, what is the required sample size if the error is to be less than ½ hour with a 95% level of confidence?

Accepted Answer

A)  554 
B)  130 
C)  35 
D)  393 
E)  None of the choices are correct 
A)  554 
B)  130 
C)  35 
D)  393 
E)  None of the choices are correct

Question 11

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 40 messages that were not business related. The 95%
Confidence interval for the population proportion is:

Accepted Answer

A)  0.199 to 0.201 
B)  0.101 to 0.199 
C)  0.07060 to.1029 
D)  0.0753 to 0.1247 
E)  0.0700 to 0.1000 
A)  0.199 to 0.201 
B)  0.101 to 0.199 
C)  0.07060 to.1029 
D)  0.0753 to 0.1247 
E)  0.0700 to 0.1000

Question 12

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 90% confidence interval, what is the critical value needed?

Accepted Answer

A)  t = 1.753 
B)  t = 2.131 
C)  t = 2.947 
D)  z = 1.645 
E)  z = 1.96 
A)  t = 1.753 
B)  t = 2.131 
C)  t = 2.947 
D)  z = 1.645 
E)  z = 1.96

Question 13

i. The t distribution is positively skewed. 
ii. All t distributions have the same mean of zero and a standard deviation of 1.
Iii) The t distribution is more spread out and flatter at the center than is the standard normal distribution. However, as the sample size increases, the t distribution curve approaches the standard normal distribution.

Accepted Answer

A)  (i), (ii) and (iii) are all correct statements 
B)  (iii) is a correct statement but not (i) or (ii). 
C)  (i) and, (iii) are correct statements but not (ii). 
D)  (ii) and, (iii) are correct statements but not (i). 
E)  All statements are false 
A)  (i), (ii) and (iii) are all correct statements 
B)  (iii) is a correct statement but not (i) or (ii). 
C)  (i) and, (iii) are correct statements but not (ii). 
D)  (ii) and, (iii) are correct statements but not (i). 
E)  All statements are false

Question 14

A consumer group would like to estimate the mean monthly electricity charge for a single family house in July (within $5) using a 99 percent level of confidence. Based on similar studies the standard deviation is estimated to be $20.00. How large a sample is required?

Accepted Answer

A)  105 
B)  106 
C)  107 
D)  108 
E)  109 
A)  105 
B)  106 
C)  107 
D)  108 
E)  109

Question 15

Recently, a university surveyed recent graduates of the English Department for their starting salaries. One hundred graduates returned the survey. The average salary was $35,000 with a standard deviation of $2,000.
What is the best point estimate of the population mean?

Accepted Answer

A)  $25,000 
B)  $2,000 
C)  $500 
D)  $400 
E)  $35,000 
A)  $25,000 
B)  $2,000 
C)  $500 
D)  $400 
E)  $35,000

Question 16

If 2,000 card-carrying members of a political party were randomly sampled, and 1,600 said they wanted a change in leadership, what is the 95% confidence interval for the true population percentage for all of the card-carrying members of the party who wanted a change in leadership?

Accepted Answer

A)  78.2% to 81.8% 
B)  78.0% to 82.0% 
C)  76.5% to 83.5% 
D)  77.7% to 82.3% 
E)  less than 50% 
A)  78.2% to 81.8% 
B)  78.0% to 82.0% 
C)  76.5% to 83.5% 
D)  77.7% to 82.3% 
E)  less than 50%

Question 17

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

Accepted Answer

A)  172 
B)  127 
C)  217 
D)  61 
E)  Over 500 
A)  172 
B)  127 
C)  217 
D)  61 
E)  Over 500

Question 18

The following summarizes the average price of Air Canada stock at the end of 20 randomly selected weeks in 2000.   Determine a 90% confidence interval for the average Air Canada stock price in 2000.

Accepted Answer

A)  [16.23, 18.55] 
B)  [14.90, 19.87] 
C)  [17.48, 19.40] 
D)  [16.43, 18.35] 
E)  Unable to determine from the information given 
A)  [16.23, 18.55] 
B)  [14.90, 19.87] 
C)  [17.48, 19.40] 
D)  [16.43, 18.35] 
E)  Unable to determine from the information given

Question 19

A statistics professor wishes to estimate the average mark on a term test for a course that has multiple sections and many students. A survey of some of the students registered for the course reveals the following results:   The student from the course wonders whether the population mean could have been 60 or 80.

Accepted Answer

A)  Since 80 is within the 95% confidence interval, the population mean is likely to be 80. 
B)  Since 80 is not within the 95% confidence interval, the population mean is not likely to be 80. 
C)  Since 60 is within the 95% confidence interval, the population mean is likely to be 60. 
D)  Since neither 60 nor 80 is within the 95% confidence interval, the population mean is not likely to be 60 or 80. 
E)  B & C are true 
A)  Since 80 is within the 95% confidence interval, the population mean is likely to be 80. 
B)  Since 80 is not within the 95% confidence interval, the population mean is not likely to be 80. 
C)  Since 60 is within the 95% confidence interval, the population mean is likely to be 60. 
D)  Since neither 60 nor 80 is within the 95% confidence interval, the population mean is not likely to be 60 or 80. 
E)  B & C are true

Question 20

The Kennel Club wants to estimate the proportion of children that have a dog as a pet. Assume a 95% level of confidence and that the club estimates that 30% of the children have a dog as a pet. If the club wants the estimate to be within 3% of the population proportion, how many children would they need to contact?

Accepted Answer

A)  978 
B)  879 
C)  789 
D)  987 
E)  897 
A)  978 
B)  879 
C)  789 
D)  987 
E)  897

A sample standard deviation is the best point estimate of the

The following summarizes the average price of Air Canada stock at the end of 20 randomly selected weeks in 2000.

A sample of 20 is selected from the population. What is the number of degrees of freedom used to determine the appropriate critical t-value?

A 95% confidence interval infers that the population mean

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. Develop a 95% confidence interval for the mean annual consumption of sugar.

A survey of 144 retail stores revealed that the average price of a DVD was $375 with a standard error of $20. What is the 95% confidence interval to estimate the true cost of the DVD?

Reasoning from a sample or small group to the entire group or population is called_________

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 40 messages that were not business related. The 95% Confidence interval for the population proportion is:

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 90% confidence interval, what is the critical value needed?

A consumer group would like to estimate the mean monthly electricity charge for a single family house in July (within $5) using a 99 percent level of confidence. Based on similar studies the standard deviation is estimated to be $20.00. How large a sample is required?

Recently, a university surveyed recent graduates of the English Department for their starting salaries. One hundred graduates returned the survey. The average salary was $35,000 with a standard deviation of $2,000. What is the best point estimate of the population mean?

If 2,000 card-carrying members of a political party were randomly sampled, and 1,600 said they wanted a change in leadership, what is the 95% confidence interval for the true population percentage for all of the card-carrying members of the party who wanted a change in leadership?

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

The following summarizes the average price of Air Canada stock at the end of 20 randomly selected weeks in 2000. Determine a 90% confidence interval for the average Air Canada stock price in 2000.

What Is Statistics

Describing Data: Frequency Distributions and Graphic Presentation

Describing Data: Numerical Measures

A Survey of Probability Concepts

Discrete Probability Distributions

The Normal Probability Distribution

Sampling Methods and the Central Limit Theorem

One-Sample Tests of a Hypothesis

Two-Sample Tests of Hypothesis

Analysis of Variance

Linear Regression and Correlation

Multiple Regression and Correlation Analysis

Chi-Square Applications for Nominal Data

Index Numbers

Time Series and Forecasting

An Introduction to Decision Theory

Filters

Exam 8: Estimation and Confidence Intervals

A sample standard deviation is the best point estimate of the

The following summarizes the average price of Air Canada stock at the end of 20 randomly selected weeks in 2000.

A sample of 20 is selected from the population. What is the number of degrees of freedom used to determine the appropriate critical t-value?

A 95% confidence interval infers that the population mean

A survey of 144 retail stores revealed that the average price of a DVD was $375 with a standard error of $20. What is the 95% confidence interval to estimate the true cost of the DVD?

Reasoning from a sample or small group to the entire group or population is called_________

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 40 messages that were not business related. The 95% Confidence interval for the population proportion is:

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 90% confidence interval, what is the critical value needed?

A consumer group would like to estimate the mean monthly electricity charge for a single family house in July (within $5) using a 99 percent level of confidence. Based on similar studies the standard deviation is estimated to be $20.00. How large a sample is required?

Recently, a university surveyed recent graduates of the English Department for their starting salaries. One hundred graduates returned the survey. The average salary was $35,000 with a standard deviation of $2,000. What is the best point estimate of the population mean?

If 2,000 card-carrying members of a political party were randomly sampled, and 1,600 said they wanted a change in leadership, what is the 95% confidence interval for the true population percentage for all of the card-carrying members of the party who wanted a change in leadership?

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

The following summarizes the average price of Air Canada stock at the end of 20 randomly selected weeks in 2000. Determine a 90% confidence interval for the average Air Canada stock price in 2000.

What Is Statistics

Describing Data: Frequency Distributions and Graphic Presentation

Describing Data: Numerical Measures

A Survey of Probability Concepts

Discrete Probability Distributions

The Normal Probability Distribution

Sampling Methods and the Central Limit Theorem

One-Sample Tests of a Hypothesis

Two-Sample Tests of Hypothesis

Analysis of Variance

Linear Regression and Correlation

Multiple Regression and Correlation Analysis

Chi-Square Applications for Nominal Data

Index Numbers

Time Series and Forecasting

An Introduction to Decision Theory

Filters