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Confidence Intervals Quiz 3 (25 MCQs)

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1. Construct a 90% confidence interval of a random sample size of 19 cows with a mean of 155.526 and a standard deviation of 19.993.
2. Given the Critical Value of Z = 2.11, find the Confidence Level.
3. Most 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 400 students and find that 317 can roll their tongues. The margin of error for a 95% confidence interval for the true proportion of tongue rollers among students is closest to
4. The football coach randomly selected ten players and timed how long each player took to perform a certain drill. The times (in minutes) were:13.2, 5.1, 7.5, 8.0, 12.7, 7.6, 13.8, 14.5, 7.7, and 10.5. Determine a 95 percent confidence interval for the mean time for all players.
5. Mr. Kellar's class would like to estimate the mean number of times females interact with Instagram at Northland. Find a 95% confidence interval based on the data students gathered:10, 15, 20, 8, 7, 5, 15, 20, 7, 8, 9, 6
6. Determine the sampling error if the grade point averages for 10 randomly selected students from a class of 125students has a mean of x = 2.3. Assume the grade point average of the 125 students has a mean of $\mu$ = 2.7.
7. The _____ is the maximum likely difference between the point estimate of a parameter and the actual value of the parameter.
8. Find the minimum sample size needed to be 4% within the true proportion if you are 95% confident and p-hat = 0.6
9. It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the true proportion of teenage boys who have received speeding tickets?
10. A laboratory tested 72 candy bars found in vending machines and found that the mean number of calories was 240 with s = 19.6 calories. Construct a 95% confidence interval for the mean calories of all candy bars found in vending machines.
11. If the population standard deviation is unknown which distribution should be used to find a confidence interval for a mean?
12. In a survey of 104 students, it was found that 79 went to the homecoming game this year. Find p-hat first and use z formula with p-hat in it.Calculate a 99% confidence interval for p.
13. Find the critical value Zc that corresponds to a 98% confidence level
14. A research company wants to estimate the proportion of people who like oatmeal. They want the confidence level to be 95%. The company gets 325 people to sign up for the survey, but on the day that the survey is issued, only 250 people show up and take the survey. What happens to the confidence interval?
15. A random sample of 15 DVD players has a mean price of $ 64.30 and a standard deviation of $ 5.60. Find a 95% confidence interval for the mean price of all DVD players.
16. Choose the appropriate type of confidence interval for the situation described below.A random sample of 9 refrigerators has a mean cost of $ 1263 and a standard deviation of $ 530.75. Construct a 90% confidence interval for the average cost of a refrigerator.
17. In a recent study of 42 eighth graders, the mean number of hours per week that they watched television was19.6. Assume the population standard deviation is 5.8 hours. Find the 98% confidence interval for thepopulation mean.
18. Find the Critical Value for an 86% Confidence Level.
19. A nutritionist found that in a sample of 80 families, 22% said they are apples at least once a week. Construct the 90% CI for the population proportion.
20. The standard IQ test has a mean of 97 and a standard deviation of 17. We want to be 95% certain that we arewithin 5 IQ points of the true mean. Determine the required sample size.
21. The lifetime of a certain type of batter is known to be normally distributed with a standard deviation of 20 hours. A sample of 50 batteries had a mean lifetime of 120.1 hours. It is desired to construct a 99% confidence interval for the mean lifetime of this type of battery.What is the Confidence Interval to one decimal place?
22. An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.Find the Margin of Error to two decimal places.
23. A random sample of 100 Woodrow students found that 53 of them were in possession of a pencil. Create a 90% confidence interval for this sample.
24. Which of the following is an example of an interval estimate?
25. A random sample of 100 visitors to a popular theme park spent an average of $ 142 on the trip with a sample standard deviation of $ 47.50. Which of the following would be the 98% confidence interval for the mean money spent by all visitors to this theme park?
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