Transcript PPT Chapter 10

Active Learning Lecture Slides
For use with Classroom Response Systems
Chapter 10:
Confidence Intervals for Proportions
Business Statistics
First Edition
by Sharpe, De Veaux, Velleman
Copyright © 2010 Pearson Education, Inc.
Slide 10- 1
The higher the level of confidence we want, the
narrower our confidence interval becomes.
A. True
B. False
Copyright © 2010 Pearson Education, Inc.
Slide 10- 2
The higher the level of confidence we want, the
narrower our confidence interval becomes.
A. True
B. False
Copyright © 2010 Pearson Education, Inc.
Slide 10- 3
In constructing a confidence interval for a
proportion, we add and subtract the _________
from the sample proportion.
A. margin of error
B. critical value
C. confidence level
D. standard error
Copyright © 2010 Pearson Education, Inc.
Slide 10- 4
In constructing a confidence interval for a
proportion, we add and subtract the _________
from the sample proportion.
A. margin of error
B. critical value
C. confidence level
D. standard error
Copyright © 2010 Pearson Education, Inc.
Slide 10- 5
The Success/Failure Condition that ensures the
sample size is large enough to use the Central
Limit Theorem has the expectation of at least
____ “successes” and ____ “failures.”
A. 5
B. 10
C. 15
D. 25
Copyright © 2010 Pearson Education, Inc.
Slide 10- 6
The Success/Failure Condition that ensures the
sample size is large enough to use the Central
Limit Theorem has the expectation of at least
____ “successes” and ____ “failures.”
A. 5
B. 10
C. 15
D. 25
Copyright © 2010 Pearson Education, Inc.
Slide 10- 7
We have calculated a 95% confidence interval and
would prefer to have a smaller margin of error without
losing any confidence. In order to do this, we can
I. change the z∗ value to a smaller number.
II. take a larger sample.
III. take a smaller sample.
A. I only
B. II only
C. III only
D. I and II
Copyright © 2010 Pearson Education, Inc.
Slide 10- 8
We have calculated a 95% confidence interval and
would prefer to have a smaller margin of error without
losing any confidence. In order to do this, we can
I. change the z∗ value to a smaller number.
II. take a larger sample.
III. take a smaller sample.
A. I only
B. II only
C. III only
D. I and II
Copyright © 2010 Pearson Education, Inc.
Slide 10- 9
Which is true about a 98% confidence interval for a
population proportion based on a given sample?
I. We are 98% confident that the sample proportion is
in our interval.
II. The interval is narrower than a 95% confidence
interval.
III. The interval is wider than a 95% confidence
interval.
A. I only
B. II only
C. III only
D. I and II
Copyright © 2010 Pearson Education, Inc.
Slide 10- 10
Which is true about a 98% confidence interval for a
population proportion based on a given sample?
I. We are 98% confident that the sample proportion is
in our interval.
II. The interval is narrower than a 95% confidence
interval.
III. The interval is wider than a 95% confidence
interval.
A. I only
B. II only
C. III only
D. I and II
Copyright © 2010 Pearson Education, Inc.
Slide 10- 11
We have calculated a confidence interval based on a
sample of size n = 100. Now we want to get a better
estimate with a margin of error that is only one-fourth
as large. How large does our new sample need to be?
A. 50
B. 200
C. 400
D. 1600
Copyright © 2010 Pearson Education, Inc.
Slide 10- 12
We have calculated a confidence interval based on a
sample of size n = 100. Now we want to get a better
estimate with a margin of error that is only one-fourth
as large. How large does our new sample need to be?
A. 50
B. 200
C. 400
D. 1600
Copyright © 2010 Pearson Education, Inc.
Slide 10- 13
A news poll which estimated that 82% of all voters
believe global warming exists had a margin of error of
+/- 3%. Suppose an environmental group planning a
follow-up survey on this issue wants to determine a
95% confidence interval with a margin of error of no
more than 2%. How large a sample do they need?
A. 32
B. 1418
C. 999
D. 38
Copyright © 2010 Pearson Education, Inc.
Slide 10- 14
A news poll which estimated that 82% of all voters
believe global warming exists had a margin of error of
+/- 3%. Suppose an environmental group planning a
follow-up survey on this issue wants to determine a
95% confidence interval with a margin of error of no
more than 2%. How large a sample do they need?
A. 32
B. 1418
C. 999
D. 38
Copyright © 2010 Pearson Education, Inc.
Slide 10- 15
A large multinational corporation recently
implemented an ERP system. A survey was done to
determine the level of satisfaction with the new
system. Out of 350 managers surveyed, 280
indicated that they were satisfied. What is the
standard error for the proportion of satisfied
managers?
A. 0.20
B. 0.80
C. 0.16
D. 0.02
Copyright © 2010 Pearson Education, Inc.
Slide 10- 16
A large multinational corporation recently
implemented an ERP system. A survey was done to
determine the level of satisfaction with the new
system. Out of 350 managers surveyed, 280
indicated that they were satisfied. What is the
standard error for the proportion of satisfied
managers?
A. 0.20
B. 0.80
C. 0.16
D. 0.02
Copyright © 2010 Pearson Education, Inc.
Slide 10- 17
A large multinational corporation recently
implemented an ERP system. A survey was done to
determine the level of satisfaction with the new
system. Out of 350 managers surveyed, 280
indicated that they were satisfied. At 95%
confidence, what is the margin of error for the
proportion of satisfied managers?
A. +/- 1.5680
B. +/- 0.0392
C. +/- 0.3136
D. +/- 0.0515
Copyright © 2010 Pearson Education, Inc.
Slide 10- 18
A large multinational corporation recently
implemented an ERP system. A survey was done to
determine the level of satisfaction with the new
system. Out of 350 managers surveyed, 280
indicated that they were satisfied. At 95%
confidence, what is the margin of error for the
proportion of satisfied managers?
A. +/- 1.5680
B. +/- 0.0392
C. +/- 0.3136
D. +/- 0.0515
Copyright © 2010 Pearson Education, Inc.
Slide 10- 19