Question 1

How is the unbiasness of estimators defined?

Accepted Answer

A) An estimator is unbiased if its expected value equals the estimated population parameter. 
B) An unbiased estimator approaches the estimated population parameter as the sample size grows larger. 
C) An estimator is unbiased if it always gives the correct value of the estimated population parameter. 
D) An estimator is unbiased if its standard error is lower than that of other estimators of the estimated population parameter. 
A) An estimator is unbiased if its expected value equals the estimated population parameter. 
B) An unbiased estimator approaches the estimated population parameter as the sample size grows larger. 
C) An estimator is unbiased if it always gives the correct value of the estimated population parameter. 
D) An estimator is unbiased if its standard error is lower than that of other estimators of the estimated population parameter.

Question 2

A researcher in campaign finance law wants to estimate the proportion of elementary,middle,and high school teachers who contributed to a candidate during a recent election cycle.Given that no prior estimate of the population proportion is available,what is the minimum sample size such that the margin of error is no more than 0.03 for a 95% confidence interval?

Accepted Answer

A) 751.67 
B) 752 
C) 1067.11 
D) 1068 
A) 751.67 
B) 752 
C) 1067.11 
D) 1068

Question 3

Exhibit 8.4.According to a report in USA Today (February 1,2012),more and more parents are helping their young adult children get homes.Suppose 8 persons in a random sample of 40 young adults who recently purchased a home in Kentucky got help from their parents.You have been asked to construct a 95% confidence interval for the population proportion of all young adults in Kentucky who got help from their parents. Refer to Exhibit 8.4.If a 99% confidence interval is constructed instead of a 95% confidence interval for the population proportion,then ____________________.

Accepted Answer

A) The resulting margin of error will increase and the risk of reporting an incorrect interval will increase 
B) The resulting margin of error will decrease and the risk of reporting an incorrect interval will increase 
C) The resulting margin of error will increase and the risk of reporting an incorrect interval will decrease 
D) The resulting margin of error will decrease and the risk of reporting an incorrect interval will decrease 
A) The resulting margin of error will increase and the risk of reporting an incorrect interval will increase 
B) The resulting margin of error will decrease and the risk of reporting an incorrect interval will increase 
C) The resulting margin of error will increase and the risk of reporting an incorrect interval will decrease 
D) The resulting margin of error will decrease and the risk of reporting an incorrect interval will decrease

Question 4

Given a sample mean of 27 and a sample standard deviation of 3.5 computed from a sample of size 36,find a 95% confidence interval on the population mean.

Accepted Answer

A) [25.8158,28.1842] 
B) [25.8170,28.1830] 
C) [26.0142,27.9858] 
D) [26.9930,27.0070] 
A) [25.8158,28.1842] 
B) [25.8170,28.1830] 
C) [26.0142,27.9858] 
D) [26.9930,27.0070]

Question 5

Newscasters wish to predict the outcome of the next presidential election with 99% confidence and a margin of error equal to 0.08.Find the appropriate sample size to accomplish this goal.

Accepted Answer

The answer of Newscasters wish to predict the outcome of...

Question 6

Find the minimum sample size when we want to construct a 90% confidence interval on the population proportion for the support of candidate A in the following mayoral election.Candidate A is facing two opposing candidates.In a preselected poll of 100 residents,22 supported her.The desired margin of error is 0.08.

Accepted Answer

A) n = 44 
B) n = 72 
C) n = 73 
D) n = 103 
A) n = 44 
B) n = 72 
C) n = 73 
D) n = 103

Question 7

Which of the following is a point estimate?

Accepted Answer

A)    
B) P 
C) μ 
D)    
A)    
B) P 
C) μ 
D)

Question 8

Exhibit 8-6.A sample of 1400 American households was asked if they planned to buy a new car next year.Of the respondents,34% indicated they planned to buy a new car next year. Refer to Exhibit 8-6.Construct a 90% confidence interval of the proportion of American households who expect to buy a new car next year.

Accepted Answer

A) [0.3152,0.3648] 
B) [0.3191,0.3609] 
C) [0.3394,0.3406] 
D) [0.3354,0.3446] 
A) [0.3152,0.3648] 
B) [0.3191,0.3609] 
C) [0.3394,0.3406] 
D) [0.3354,0.3446]

Question 9

Suppose taxi fare from Logan Airport to downtown Boston is known to be normally distributed with a standard deviation of $2.50.The last seven times John has taken a taxi from Logan to downtown Boston the fares have been $22.10,$23.25,$21.35,$24.50,$21.90,$20.75,and $22.65.What is a 95% confidence interval for the population mean taxi fare?

Accepted Answer

A) [$17.4571,$27.2571] 
B) [$20.5051,$24.2091] 
C) [$20.8027,$23.9115] 
D) [$21.6571,$23.0571] 
A) [$17.4571,$27.2571] 
B) [$20.5051,$24.2091] 
C) [$20.8027,$23.9115] 
D) [$21.6571,$23.0571]

Question 10

The Department of Education wishes to estimate average SAT score among U.S.high school students.How many students would they have to sample,given that the test has a known population standard deviation of 100,in order to ensure that the margin of error was no more than 20 for a 99% confidence interval?

Accepted Answer

The answer of The Department of Education wishes to estimate...

Question 11

In an examination of purchasing patterns of shoppers,a sample of 16 shoppers revealed that they spent,on average,$54 per hour of shopping.Based on previous years,the population standard deviation is thought to be $21 per hour of shopping.Assuming that the amount spent per hour of shopping is normally distributed,find a 90% confidence interval for the mean amount.

Accepted Answer

A) [45.3637,62.6363] 
B) [47.2695,60.7305] 
C) [51.8409,56.1591] 
D) [52.3174,55.6826] 
A) [45.3637,62.6363] 
B) [47.2695,60.7305] 
C) [51.8409,56.1591] 
D) [52.3174,55.6826]

How is the unbiasness of estimators defined?

Given a sample mean of 27 and a sample standard deviation of 3.5 computed from a sample of size 36,find a 95% confidence interval on the population mean.

Newscasters wish to predict the outcome of the next presidential election with 99% confidence and a margin of error equal to 0.08.Find the appropriate sample size to accomplish this goal.

Which of the following is a point estimate?

Statistics and Data

Tabular and Graphical Methods

Numerical Descriptive Measures

Basic Probability Concepts

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Testing

Statistical Inference Concerning Two Populations

Statistical Inference Concerning Variance

Chi-Square Tests

Analysis of Variance

Regression Analysis

Inference With Regression Models

Regression Models for Nonlinear Relationships

Regression Models With Dummy Variables

Time Series and Forecasting

Returns, Index Numbers and Inflation

Nonparametric Tests

Filters

Exam 8: Interval Estimation

How is the unbiasness of estimators defined?

Given a sample mean of 27 and a sample standard deviation of 3.5 computed from a sample of size 36,find a 95% confidence interval on the population mean.

Newscasters wish to predict the outcome of the next presidential election with 99% confidence and a margin of error equal to 0.08.Find the appropriate sample size to accomplish this goal.

Which of the following is a point estimate?

Statistics and Data

Tabular and Graphical Methods

Numerical Descriptive Measures

Basic Probability Concepts

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Testing

Statistical Inference Concerning Two Populations

Statistical Inference Concerning Variance

Chi-Square Tests

Analysis of Variance

Regression Analysis

Inference With Regression Models

Regression Models for Nonlinear Relationships

Regression Models With Dummy Variables

Time Series and Forecasting

Returns, Index Numbers and Inflation

Nonparametric Tests

Filters