A newsgroup is interested in constructing a 90% confidence
interval for the difference in the proportions of Texans and New
Yorkers who favor a new Green initiative. Of the 506 randomly
selected Texans surveyed, 436 were in favor of the initiative and
of the 525 randomly selected New Yorkers surveyed, 459 were in
favor of the initiative.
a. With 90% confidence the difference in the proportions of Texans
and New Yorkers who favor a new Green initiative is between _______...
A newsgroup is interested in constructing a 90% confidence
interval for the difference in the proportions of Texans and New
Yorkers who favor a new Green initiative. Of the 582 randomly
selected Texans surveyed, 428 were in favor of the initiative and
of the 569 randomly selected New Yorkers surveyed, 456 were in
favor of the initiative.
. With 90% confidence the difference in the proportions of
Texans and New Yorkers who favor a new Green initiative is between
(round...
Construct the indicated confidence interval for the difference
between population proportions p1 - p2. Assume that the samples are
independent and that they have been randomly selected.
4) x1 = 44, n1 = 64 and x2 = 50, n2 = 73; Construct a 95%
confidence interval for the difference 4) between population
proportions p1 - p2.
A 95% confidence interval for a difference in proportions p1-p2
if the samples have n1=60 with p^1=0.69 and n2=60 with p^2=0.56,
and the standard error is SE=0.09.
Use the two-proportions z-interval procedure to obtain
the required confidence interval for the difference between two
population proportions. Assume that independent simple random
samples have been selected from the two populations.
A survey of students at one college found that 57 of 96 randomly
selected freshmen and 85 of 118 randomly selected sophomores lived
off campus. Find a 98% confidence interval for the difference
between the proportions of freshmen and sophomores at this college
who live off campus.
-0.278 to...
a) If the confidence interval for the difference in population
proportions p1 - p2 includes 0, what does this imply?
b) If all the values of a confidence interval for two population
proportions are positive, then what does this imply?
c) If all the values of a confidence interval for two population
proportions are negative, then what does this imply?
d) Explain the difference between sampling with replacement and
sampling without replacement. Suppose you had the names of...
Construct the indicated confidence interval for the difference between the two population means. Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. Independent samples from two different populations yield the following data. The sample size is 478 for both samples. Find the \(85 \%\) confidence interval for \(\mu_{1}-\mu_{2}\).
\(\bar{x}_{1}=958, \bar{x}_{2}=157, s_{1}=77, s_{2}=88\)
A. \(800<\mu_{1}-\mu_{2}<802\)
B. \(791<\mu_{1}-\mu_{2}<811\)
C. \(793<\mu_{1}-\mu_{2}<809\)
D. \(781<\mu_{1}-\mu_{2}<821\)
Activity 4: Confidence interval for a difference in proportions
We will use StatKey to calculate a confidence Interval for a
difference in proportions using the StatKey dataset “Use Text
Messages (by age)”, which compares text messaging use between teens
and adults.
1. Create a bootstrap distribution of 4000 bootstrap differences
of proportions using this sample. Use the "Two-tail" option to find
the boundaries giving 95% in the middle of the bootstrap
distribution.
2. What is the difference in sample proportions...
If you wanted to calculate a 90% confidence interval for the
difference in average
number of friendship contacts between primary aged boys and girls
and we are
pretending that df=12, what t scores would you use? (assuming equal
variances again)
A. ☐+/- 1.356
B. ☐+/- 2.681
C. ☐+/- 1.782
D. ☐+/- 2.179
E. ☐+/- 3.055
9. Suppose you calculated your 90% interval as described above and
your lower
confidence limit was
–2.75 and your upper confidence limit was 3.20. What...