MGMT 650 Problem Set 3- Confidence Interval

MGMT 650 Fall 2016 Problem Set 3(Last updated 9/19/2016)1. Confidence Interval:Compute a 95% confidence interval for the populationmean, based on the sample numbers 21, 22, 33, 34, 25,26, and 139.Change the last value to 29 and re-compute theconfidence interval.What is an outlier and how does it affect the confidenceinterval?2. Confidence Interval:A sample from a normal population has size = 109observations, mean = 7.99, and standard deviation =3.67. What is the 95 percent confidence interval for thepopulation mean? Use the Excel function,=CONFIDENCE.NORM() and the mean to find the twolimits.3. Confidence Limit:The director of admissions at the University of Maryland,University College is concerned about the high cost oftextbooks for the students each semester. A sample of 25students enrolled in the university indicates that x(bar) =$315.40 and s = $43.20.a. Using the .10 level of significance, is there evidencethat the population mean is above $300?b. What is your answer if x(bar) = $315.40, s = $75.00,and the level of significance is 0.05?c. What is your answer if x(bar) = $305.11, s = $43.20,and the level of significance is 0.10?d. D. Based on the information in part a, what decisionshould the director make about the books used for thecourses if the goal is to keep the cost below $300?4. t-Test: Paired Two Sample for MeansIn week 7 we will study Hypothesis Testing in detail.For answering the following question, you need a brief idea of whathypothesis testing is. Please read the following introduction:http://www.socialresearchmethods.net/kb/hypothes.phpThe director for Weight Watchers International wants to determine ifthe changes in their program results in better weight loss. Sheselected 25 Weight Watcher members at random and compared theirweight 6 months later to weight at the start of the program. Here arethe results: (The weight in the column labeled “After” represents theirweights six months later and “Before” represents their weight at thestart of the six­month period.) The director used .05 as thesignificance level.Use Excel to test H0: After – Before ? 0 vs. HA: After – Before < 0.For each paired difference, compute After – Before. In Data Analysis,t­Test: Paired Two Sample for means, select the After data forVariable 1 Range. Note that the critical value output by Data Analysisfor this test is always positive. In this problem, the sign of the criticalvalue is negative corresponding to a 1­tailed test with lower rejectregion and negative lower critical value. State your conclusion.Person12Before176192After164191345678910111213141516171819202122232425185177196178196181158201191193176212177183210198157213161177210192178176176185169196172158193185189175210173180204192152200161166203186170