Intro Stats
4th Edition
ISBN: 9780321825278
Author: Richard D. De Veaux, Paul F. Velleman, David E. Bock
Publisher: PEARSON
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Chapter 16, Problem 34E
Back to campus ACT, Inc. reported that 74% of 1644 randomly selected college freshmen returned to college the next year. The study was stratified by type of college—public or private. The retention rates were 71.9% among 505 students enrolled in public colleges and 74.9% among 1139 students enrolled in private colleges.
- a) Will the 95% confidence interval for the true national retention rate in private colleges be wider or narrower than the 95% confidence interval for the retention rate in public colleges? Explain.
- b) Do you expect the margin of error for the overall retention rate to be larger or smaller? Explain.
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A company reported that 76% of 1700 randomly selected college freshmen returned to college the next year. The study was stratified by type of college-public or private. The retention rates were 72.7% among 510 students enrolled in public colleges and 77.4% among 1190
students enrolled in private colleges. The company found 95% confidence intervals for retention rates. Suppose that the company wants to update its information on the percentage of freshmen that return for a second year of college. Complete parts a and b below.
a) It wants to cut the stated margin of error in half. How many college freshmen must be surveyed?
(Type a whole number.)
b) Do you have any concerns about this sample? Explain.
Select all that apply.
A. Because the sample is stratified, there is a greater risk of greater sampling error.
B. The sample size is very small, which may reduce the level of certainty associated with the interval.
C. Because the sample is stratified, the Independence Assumption may be…
A doctor would like to estimate the mean difference in the number of hours of sleep for seniors in high school and seniors in college. To do so, he selects a random sample of 50 high school seniors from all high schools in his county. He also selects a random sample of 50 seniors from the colleges in his county. He would like to construct a 95% confidence interval for the true mean difference in the number of hours of sleep for seniors in high school and seniors in college. Are the conditions for inference met?
Yes, all three conditions for inference are met.
No, the random condition is not met for both samples.
No, the 10% condition is not met for both samples.
No, the Normal/large sample condition is not met for both samples.
A company reported that 72% of 1691 randomly selected college freshmen returned to college the next year. The study was stratified by type of college—public or private. The retention rates were 67.8% among 534 students enrolled in public colleges and 74.0% among 1157 students enrolled in private colleges. The company found 95% confidence intervals for retention rates. Suppose that the company wants to update its information on the percentage of freshmen that return for a second year of college. Complete parts a and b below.
A) It wants to cut the stated margin of error in half. How many college freshmen must be surveyed?
b) Do you have any concerns about this sample? Explain.
Select all that apply.
A.
The 10% Condition would probably be violated by this sample.
B.
Because the sample is stratified, there is a greater risk of greater sampling error.
C.
Because the sample is stratified, the Independence Assumption may be violated.
D.
The…
Chapter 16 Solutions
Intro Stats
Ch. 16.1 - A Pew Research study regarding cell phones asked...Ch. 16.1 - Prob. 2JCCh. 16.1 - A Pew Research study regarding cell phones asked...Ch. 16.1 - Prob. 4JCCh. 16.1 - Prob. 5JCCh. 16.2 - Prob. 6JCCh. 16.2 - Prob. 7JCCh. 16.2 - Prob. 8JCCh. 16 - Prob. 1ECh. 16 - Prob. 2E
Ch. 16 - Prob. 3ECh. 16 - Prob. 4ECh. 16 - Prob. 5ECh. 16 - 6. I asked, “How’s life?” In the Gallup poll...Ch. 16 - Prob. 7ECh. 16 - Prob. 8ECh. 16 - Margin of error A TV newscaster reports the...Ch. 16 - Another margin of error A medical researcher...Ch. 16 - Conditions For each situation described below,...Ch. 16 - More conditions Consider each situation described....Ch. 16 - Conclusions A catalog sales company promises to...Ch. 16 - More conclusions In January 2002, two students...Ch. 16 - Confidence intervals Several factors are involved...Ch. 16 - Confidence intervals, again Several factors are...Ch. 16 - Cars What fraction of cars made in Japan? The...Ch. 16 - Prob. 18ECh. 16 - Prob. 19ECh. 16 - Prob. 20ECh. 16 - Prob. 21ECh. 16 - Prob. 22ECh. 16 - 23. Contributions, please The Paralyzed Veterans...Ch. 16 - Take the offer First USA, a major credit card...Ch. 16 - Teenage drivers An insurance company checks police...Ch. 16 - Junk mail Direct mail advertisers send...Ch. 16 - Prob. 27ECh. 16 - Prob. 28ECh. 16 - Prob. 29ECh. 16 - Gambling A city ballot includes a local initiative...Ch. 16 - Rickets Vitamin D, whether ingested as a dietary...Ch. 16 - Teachers A 2011 Gallup poll found that 76% of...Ch. 16 - Prob. 33ECh. 16 - Back to campus ACT, Inc. reported that 74% of 1644...Ch. 16 - Deer ticks Wildlife biologists inspect 153 deer...Ch. 16 - Prob. 36ECh. 16 - Graduation Its believed that as many as 25% of...Ch. 16 - Hiring In preparing a report on the economy, we...Ch. 16 - Prob. 39ECh. 16 - Prob. 40ECh. 16 - Prob. 41ECh. 16 - Another pilot study During routine screening, a...Ch. 16 - Prob. 43ECh. 16 - Amendment A TV news reporter says that a proposed...
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- A poll of 5000 residents in Brazil, Canada, China, France, Malaysia, South Africa, and the United States asked about what profession they would prefer their marriage partner to have. The choice receiving the highest percent, 805 of the responses, was doctors, nurses, and other health care professionals. Find a 99% confidence interval for the proportion of people who would prefer a doctor, nurse, or other health care professional as a marriage partner.arrow_forwardAn accounting firm has 1200 clients. From a random sample of 120 clients, 110 indicated very high satisfaction with the firm’s service. Find a 95% confidence interval for the proportion of all clients who are very highly satisfied with this firm.arrow_forwardIn a random sample of 600 adults, 270 described themselves as vegetarians. Construct a 99% confidence interval for the proportion of all adults who describe themselves as vegetarians.arrow_forward
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