Learning Materials
Features
Discover
Chapter 8: Q.5 (page 524)
You want to compute a confidence interval for the mean of a population with unknown population standard deviation. The sample size is . The value of role="math" localid="1649226392559" you would use for this interval is
(a)(b).(c)
(d) (e)
(b)
Over 30 million students worldwide already upgrade their learning with Vaia!
All the tools & learning materials you need for study success - in one app.
Get started for free
Prayer in school A New York Times/CBS News Poll asked the question, “Do you favor an amendment to the Constitution that would permit organized prayer in public schools?” Sixty-six percent of the sample answered “Yes.” The article describing the poll says that it “is based on telephone interviews conducted from Sept. 13 to Sept. 18 with adults around the United States, excluding Alaska and Hawaii. . . . The telephone numbers were formed by random digits, thus permitting access to both listed and unlisted residential numbers.” The article gives the margin of error for a confidence level as percentage points.
(a) Explain what the margin of error means to someone who knows little statistics.
(b) State and interpret the 95% confidence interval.
(c) Interpret the confidence level.
57. Critical values What critical value t* from Table B would you use for a confidence interval for the population mean in each of the following situations?
(a) A confidence interval based on observations.
(b) A confidence interval from an SRS of observations.
The Gallup Poll interviews people. Of these, say that they jog regularly. The news report adds: "The poll had a margin of error of plus or minus three percentage points at a confidence level." You can safely conclude that
(a) of all Gallup Poll samples like this one give answers withinof the true population value.
(b) the percent of the population who jog is certain to be between .
(c) of the population jog betweenof the time.
(d) we can be confident that the sample proportion is captured by the confidence interval.
(e) if Gallup took many samples,of them would find that of the people in the sample jog.
Refer to Exercise . As Gallup indicates, the percentage point margin of error for this poll includes only sampling variability (what they call “sampling error”). What other potential sources of error (Gallup calls these “non-sampling errors”) could affect the accuracy of the estimate?
High tuition costs Glenn wonders what proportion of the students at his school think that tuition is too high. He interviews an SRS of of the students at his college. Thirty-eight of those interviewed think tuition is too high.
What do you think about this solution?
We value your feedback to improve our textbook solutions.
Explanations 
Textbooks 
Exams 
GCSE 
IGCSE 
AS 
A Level 
International A Level 
University Admissions Tests 
Flashcards 
Vaia AI 
Notes 
Study Plans 
Study Sets 
Find a job 
Find a degree 
Student Deals 
Magazine 
Mobile App