Florida National University Statistics Questions

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Question 11 A food snack manufacturer samples 11 bags of pretzels off the assembly line and weighs their contents. If the sample mean is 15.2 oz. and the sample standard deviation is 0.40 oz., find the 95% confidence interval of the true mean.

Question 12 7 squirrels were found to have an average weight of 9.4 ounces with a sample standard deviation is 0.9. Find the 95% confidence interval of the true mean weight.

Question 13 The winning team's score in 13 high school basketball games was recorded. If the sample mean is 54.3 points and the sample standard deviation is 11.0 points, find the 98% confidence interval of the true mean.

Question 14 In a study of 100 new cars, 29 are white. Find and , where  is the proportion of new cars that are white.

Question 15 In a sample of 55 mice, a biologist found that 42% were able to run a maze in 30 seconds or less. Find the 90% limit for the population proportion of mice who can run a maze in 30 seconds or less.

36.5% < p < 47.5%

33.5% < p < 50.5%

31.0% < p < 53.0%

25.5% < p < 58.5%

Question 16 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?

Question 17 A report states that 46% of home owners have a vegetable garden. How large a sample is needed to estimate the true proportion of home owners who have vegetable gardens to within 4 percentage points with 92% confidence?

140

238

309

476

Question 18 John Davis, a manager of a supermarket, wants to estimate the proportion of customers who use food stamps at his store. He has no initial estimate of what the sample proportion will be. How large a sample is required to estimate the true proportion to within 3 percentage points with 98% confidence?

756

1,849

1,067

1,509

Question 19 In a sample of 855 bartenders, 48.0% report hearing complaints from patrons about their jobs. If the maximum error of estimate for the proportion of bartenders hearing job complaints is 4.4 percentage points, what is the degree of confidence used?

90%

95%

98%

99%

Question 20 For a random sample of 23 European countries, the variance on life expectancy was 7.3 years. What is the 95% confidence interval for the variance of life expectancy in all of Europe?

Question 21 What is the value for  for a 98% confidence interval when n = 12?

27.688

24.725

21.920

26.217

Question 22 What is the value for  for a 95% confidence interval when n = 18?

7.564

8.672

9.390

8.231

Question 23 4 PointsWhat is the 95% confidence interval for the standard deviation of birth weights at County General Hospital, if the standard deviation of the last 25 babies born there was 1.1 pounds?

Question 24What is the 90% confidence interval for the variance of exam scores for 28 algebra students, if the standard deviation of their last was 12.7?

Question 25Find the values for  and  when  = .05 and n = 27.

13.844 and 41.923

14.573 and 43.194

15.379 and 38.885

16.151 and 40.113