A random sample of 25 items is drawn from a population whose standard deviation is unknown. The sample mean is = 850 and the sample standard deviation is s= 15. Use Appendix D to find the values of Student's t. (a) Construct an interval estimate of u with 95% confidence. (Round your answers to 3 decimal places.) The 95% confidence interval is from to (b) Construct an interval estimate of u with 95% confidence, assuming that s 30. (Round your answers to 3 decimal places.) The 95% confidence interval is from to (c) Construct an interval estimate of u with 95% confidence, assuming that s= 60. (Round your answers to 3 decimal places.) The 95% confidence interval is from to (d) Describe how the confidence interval changes as s increases.

(1 point) A random sample of 70 observations produced a mean of a 39.5 from a population with a normal distribution and a standard deviation o = 2.14. (a) Find a 95% confidence interval for u (b) Find a 99% confidence interval for (c) Find a 90% confidence interval for

Students are reluctant to report cheating by other students. A student project put this question to an SRS of 172 undergraduates at a large university: You witness two students cheating on a quiz. Do you go to the professor? Only 19 answered "yes." What is the standard deviation of the sampling distribution of ? 0.024 0.00056 0.89 0.11

A​ person's body mass index​ (BMI) is computed by dividing the weight​ (kg) by the square of height​ (m). The accompanying table contains the BMI statistics for random samples of males and females. Assume that the two samples are independent simple random samples selected from normally distributed​populations, and do not assume that the population standard deviations are equal. Let population 1 be females.   Female​ BMI: n=69 x=29.14 s=7.41 Male​ BMI: n=79 x=28.18 s=5.24   The test statistic is   The​ P-value is     Construct a confidence interval appropriate for testing the claim in part​ (a).   The ___​% confidence interval estimate is ___<μ1−μ2<___.

You are conducting an experiment to examine the anxiety level of a group of Design Technology students. The population standard deviation o=4.8. You compute the mean and standard deviation of your sample and find that sample mean = 25.9 and sample standard deviation s = 5.3. What is the standard error of the sample mean if your sample size is 36? Give your answer to 2 decimal places.

A random sample of 15 exam scores showed a standard deviation of 6.0 points. Find the 95 percent confidence interval for the population standard deviation. Use Appendix E to obtain the values of  χ2LχL2 and χ2UχU2 . (Round your answers to 2 decimal places.) The 95% confidence interval is from ______ to __________  .

A standardized test is given to a sixth-grade class. Historically the mean score has been 151 with a standard deviation of 21. The superintendent believes that the standard deviation of performance may have recently decreased. She randomly sampled 23 students and found a mean of 161 with a standard deviation of 18.2898. Is there evidence that the standard deviation has decreased at the α=0.05 level? Step 1 of 5 : State of the hypotheses in terms of the standard deviation. Round the standard deviation to four decimal places when necessary Step 2 of 5 : Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places. Step 3 of 5 : Determine the value of the test statistic. Round your answer to three decimal places. Step 4 of 5 : Make the decision. Step 5 of 5 : What is the conclusion?

(1 point) A random sample of 110 observations produced a mean of x = 34.7 from a population with a normal distribution and a standard deviation o = 4.39. (a) Find a 99% confidence interval for u (b) Find a 95% confidence interval for (c) Find a 90% confidence interval for u

In order to formulate policy decisions informed by evidence and aimed at reducing the burden of cardiovascular disease (CVD) in Mississippi, the Governor's Task Force should initially prioritize the highest-quality evidence produced by (randomized trials, case control cities, observational cohorts, or ecological studies), followed by evidence generated by (randomized trials, case control cities, observational cohorts, or ecological studies), then by (randomized trials, case control cities, observational cohorts, or ecological studies), and finally by (randomized trials, case control cities, observational cohorts, or ecological studies)