Worksheet: Confidence Intervals for Proportions1. The paralyzed Veterans of America is a philanthropic organization that relies oncontributions. They send free mailing labels and greeting cards to potential donors ontheir list and ask for voluntary contribution. To test a new campaign they recently sentletters to a random sample of 100,000 potential donors and received 4781 donations.a) Give a 95% confidence interval for the true proportion of those from theirentire mailing list whomaydonate.b) A staff member thinks that the true rate is 5%. Given the confidence intervalyou found, do you find that percentage plausible?

Given : n=100000 x=4781 c=95%=0.95

Answered: et: Confidence Intervals for…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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9. A study of 420,082 cell phone users found that 140 of them developed cancer of the brain or nervous system. Prior to this study of cell phone use, the rate of such cancer was found to be 0.0243% for those not using cell phones. Complete parts (a) and (b). a. Use the sample data to construct a 95% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system. %
On April 15th, 1912, the R.M.S. Titanic sank into the North Atlantic Ocean, resulting in the loss of more than 1,500 passengers and crew. Below is a table which summarizes the total number of passengers and the number of survivors for the crew, first-, second-, and third-class. Find the proportion of survivors by type of service (crew, first, second, third). Test the hypothesis at the 99% confidence level that the proportion of first-class survivors is the same as third class (.25).What do you calculate for the test-statistic? What is the critical statistic? What is the conclusion of your hypothesis test? Passengers survivedCrew 885 212First 325 202Second 285 118Third 706 178Total 2201 710
PROBLEM: A psychologist asks a random sample of 30 female adolescents and a separate, random sample of 30 male adolescents how much time they spend communicating with others online on an average day. She compares the time spent communicating online of female adolescents with that of male adolescents. In your project include: The problem and data. Calculate and interpret the correct 90% confidence interval for the mean difference in the two groups average time spent communicating online. (Use the 4 steps) Preform the correct significance test to test the claim that females spend more time than males communicating online. Use a level of significance of 0.05 and then use a level of significance of 0.10. Explain your results for each alpha. (Use the 4 steps) Answer the initial question and explain how you should use the confidence interval AND significance test to answer it. Review the rubric to make sure you include all necessary components. 1. Data: Hours…
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The table shows the results of a survey in which separate samples of 400 adults each from the East, South, Midwest, and West were asked if traffic congestion is a serious problem in their community. Complete parts (a) and (b). Bad Traffic Congestion? Adults who say that traffio congestion is a serlous problem East 34% South 32% Midwest West 26% 57% ..... (a) Construct a 95% confidence interval for the proportion of adults from the Midwest who say traffic congestion is a serious problem. The 95% confidence interval for the proportion of adults from the Midwest who say traffic congestion is a serious problem is ( . ). (Round to three decimal places as needed.)
9. A researcher wants to construct a 99% confidence interval for the proportion of Americans who think that the U.S. invading Iraq was an effective step in combating world terrorism. She has no initial idea of what that proportion is. How large should her sample size be if she wants the margin of error to be at most two percent? Show or explain your thinking.
A college administrator is interested in determining the proportion of students who receive some sort of financial aid. Instead of examining the records for all students, the administrator randomly draws 120 students and finds that 48 of them are receiving financial aid. Use a 90% confidence interval to estimate the true proportion of students who receive financial aid.
The National Association of Colleges and Employers sponsors the Graduating Student and Alumni Survey.Part of the survey gauges student optimism in landing a job after graduation. According to one year’s surveyresults, published in American Demographics, among the 1218 respondents, 733 said that they expecteddifficulty finding a job. Construct a 90% confidence interval for the proportion of students who expecteddifficulty finding a job. Interpret your result.
A political scientist claims that 38% of first-year college students characterize themselves as being “moderate” or “middle of the road” as far as their political affiliation is concerned. Believing this claimed value is too high, you survey a random sample of 400 first-year college students and find that 120 characterize themselves as being “moderate” or “middle of the road.” Based on this information, what will the test statistic be? Choose the answer below that is closest to what you calculate, and try not to do a lot of rounding until you get to the very end of your calculations. 1. -0.3 2. -1.2 3. -2.6 4. -3.3 5. None of the other answer options are correct because the test statistic should be positive, not negative.
15. Pain after surgery: In a random sample of 50 patients undergoing a standard surgical procedure, 15 required medication for postoperative pain. In a random sample of 90 patients undergoing a new procedure, only 16 required pain medication. a. Construct a 95% confidence interval for the difference in the proportions of patients needing pain medication between the old and new procedures. b. A physician claims that the proportion of patients who need pain medication is the same for both procedures. Does the confidence interval contradict this claim? 16

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