Chapter 8: Q 29. (page 522)
Rating school food Latoya wants to estimate the proportion of the seniors
at her boarding school who like the cafeteria food. She interviews an SRS of of the seniors and finds that think the cafeteria food is good.
Sample size condition ofdo not meet.
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
The researcher is deciding between a confidence level and a confidence level. Compared with a confidence interval, a confidence interval will be
a. narrower and would involve a larger risk of being incorrect.
b. wider and would involve a smaller risk of being incorrect.
c. narrower and would involve a smaller risk of being incorrect.
d. wider and would involve a larger risk of being incorrect.
e. wider and would have the same risk of being incorrect.
Teens and their TV sets According to a Gallup Poll report, of teens aged to have TVs in their rooms. Here is part of the footnote to this report:
These results are based on telephone interviews with a randomly selected national sample of teenagers in the Gallup Poll Panel of households, aged to . For results based on this sample, one can say that the maximum error attributable to sampling and other random effects is percentage points. In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
a. We omitted the confidence level from the footnote. Use what you have learned to estimate the confidence level, assuming that Gallup took an SRS.
b. Give an example of a “practical difficulty” that could lead to bias in this survey.
Willows in Yellowstone Writers in some fields summarize data by giving x ̄ and its
standard error rather than .Biologists studying willow plants in Yellowstone National Park reported their results in a table with columns labeled The table entry for the heights of willow plants (in centimeters) in one region of the park was . The researchers measured a total of plants.
a. Find the sample standard deviation for these measurements.
b. A hasty reader believes that the interval given in the table is a confidence interval for the mean height of willow plants in this region of the park. Find the actual confidence level for the given interval.
Losing weight A Gallup poll asked a random sample of U.S. adults, “Would you like to lose weight?” Based on this poll, the confidence interval for the population
proportion who want to lose weight is .
a. Interpret the confidence interval.
b. What is the point estimate that was used to create the interval? What is the margin of error?
c. Based on this poll, Gallup claims that more than half of U.S. adults want to lose weight. Use the confidence interval to evaluate this claim.
A Gallup poll found that only of American adults expect to inherit money or valuable possessions from a relative. The poll’s margin of error was ±3 percentage points at a confidence level. This means that
a. the poll used a method that gets an answer within 3% of the truth about the population of the time.
b. the percent of all adults who expect an inheritance must be between and .
c. if Gallup takes another poll on this issue, the results of the second poll will lie between and .
d. there’s a 95% chance that the percent of all adults who expect an inheritance is between
25% and 31%.
e. Gallup can be 95% confident that between 25% and 31% of the sample expect an inheritance.
What do you think about this solution?
We value your feedback to improve our textbook solutions.
