Chapter 8: Q. T8.2 (page 549)
The weights (in pounds) of three adult males are,and. What is the standard error of the mean for these data?
a.
b.
c.
d.
e.
Short Answer
The standard error of the mean is
Chapter 8: Q. T8.2 (page 549)
The weights (in pounds) of three adult males are,and. What is the standard error of the mean for these data?
a.
b.
c.
d.
e.
The standard error of the mean is
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Get started for freeMost people can roll their tongues, but many can’t. The ability to roll the tongue is
genetically determined. Suppose we are interested in determining what proportion of students can roll their tongues. We test a simple random sample of students and find that can roll their tongues. The margin of error for a confidence interval for the true proportion of tongue rollers among students is closest to which of the following?
a.
b.
c.
d.
e.
Got shoes? How many pairs of shoes, on average, do female teens have? To find out, an AP Statistics class selected an SRS of female students from their school.
Then they recorded the number of pairs of shoes that each student reported having. Here
are the data:
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.
America’s favorite cookie Ann and Tori wanted to estimate the average weight of an Oreo cookie to determine if it was less than advertised (34 grams for 3 cookies). They selected a random sample of cookies and found the weight of each cookie (in grams). The mean weight was grams with a standard deviation of grams. Construct and interpret a confidence interval for the true mean weight of an Oreo cookie.
Suppose we want a 90% confidence interval for the average amount spent on books by freshmen in their first year at a major university. The interval is to have a margin of error of \(2. Based on last year’s book sales, we estimate that the standard deviation of the amount spent will be close to \)30. The number of observations required is closest to
(a) 25. (b) 30. (c) 608. (d) 609. (e) 865.
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