1 If I want to find the confidence interval for the population mean in a situation where I have a sample mean of 50 a sample standard deviation of 15 and a sample size of 20 how many degrees of freedom do I use to calculate t A 20 B 19 C 14 D 15 E Why are you using t Use z instead 2 Over many years of giving tests to many classes Professor T has estimated the population standard deviation of test scores to be 5 points In a new class we find a sample of 10 students has taken a test and scored a mean of 70 points What is the 80 confidence Interval for the mean of the points scored on the test A 67 8 to 72 2 B 68 7 to 71 3 C 68 0 to 72 0 D 66 3 to 73 7 E None of these 3 Last quarter an average of 20 students bought coffee at the beans coffee shop before 8 AM classes each day This quarter with the opening of the new coffee shop in the Anderson Academic Commons the staff at beans is worried that coffee purchases are down A sample of 12 days this quarter found a mean of 18 students and a standard deviation of 3 students purchasing coffee Create the 99 confidence interval of for the mean of students purchasing coffee this quarter A 15 3 to 20 7 B 15 49 to 20 51 C 16 1 to 19 9 D 16 4 to 19 6 E None of these For the next 4 questions use this problem description Over many years of giving tests to many classes Professor Toney has estimated the population standard deviation of test scores to be 5 points In a new class we find a sample of 10 students has taken a test and scored a mean of 79 points Does this sample tell us the mean for all students taking the test is different from the projected mean of 75 points at a 1 level of significance 4 Which statement best describes this problem A Left tail B Right tail C Two tail D None of these 5 What is the value of your calculated test statistic A 2 53 B 2 53 2 40 C A Yes B No 6 Do you reject the null hypothesis in this case D 2 40 E None of these C It is impossible to say 7 What would be a possible result of committing a Type I error in this case A Deciding to ease up on this class because they did not do very well on the test when they really B Deciding to hold off on making a choice about what to do with this class because the test was in C Feeling confident that the class has the same kind of testing score when it really does have the D Deciding to challenge this new class due to their improved outcome when they really did not do did do well error same kind of score better E None of these Use the following description for the next 4 questions Classes at the University of Denver are to be investigated for attendance are students really showing up After sampling 20 classes we find that an average of 73 of students are in each class The provost is hoping to find that students attend class more than 70 8 What is the best alternate hypothesis for this question A Ha p 7 B Ha p 7 C Ha p 7 significance A Yes B No D Ha p 7 E None of these C It is impossible to say 9 Would we conclude the students are attending class more than 70 of the time at the 5 level of 10 Based on historical data we believe that 32 of students offered admission to DU choose to attend This year 1000 out of 3400 choose to attend What is the alternate hypothesis you should use to check to see if acceptance levels have fallen 11 In past years there has been an average of 15 graduating MS Analytics students in the Daniels College of Business This year there will be 19 graduating MS Analytics students What is the alternate hypothesis you should use to see if the number of graduates is different than in the past Ha p 32 Ha mu 15 12 Classes at the University of Denver are to be investigated for attendance are students really showing up After sampling 20 classes we find that an average of 73 of students are in each class What is the 90 confidence interval for the population proportion of students in class 0 567 to 0 893 13 Last quarter an average of 20 students bought coffee at the beans coffee shop before 8 AM classes each day This quarter with the opening of the new coffee shop in the Anderson Academic Commons the staff at beans is worried that coffee purchases are down A sample of 12 days this quarter found a mean of 18 students and a standard deviation of 3 students purchasing coffee At a 1 level of significance has the number of students purchasing coffee declined What is your null hypothesis H0 What is your alternate hypothesis Ha H0 mu 20 H0 mu 20 t 2 3094 P 0 02 What is the value of your calculated test statistic z calc or t calc What is the value of p the probability associated with your calculated test statistic What should we recommend to the managers of Beans based on this test We reject the null and the number of students purchasing coffee declined A young statistics student keeps track of the amount of tips earned each shift at a local restaurant Over many years a very clear picture of what kind of tips the student will make on given days of the week emerges Above is a small part of the overall chart created by the student Please identify the best kind of test to apply for each of the questions the student has and what the best alternate hypothesis should be Here is a list of tests you could apply to the questions below Pick one for each of these scenarios A This is an ANOVA test for equality of means B This is a z test for means with known population standard deviations C This is a t test for means with paired data D This is a t test for means with unknown population standard deviations assumed unequal E This is a t test for means with unknown population standard deviations assumed equal F This is a z test for proportions Do I make the same amount in tips on all the days of the week 1 What is a good test type a letter from above for this question A 2 What is a good null hypothesis for the question all mean amount in tips are the same on the days of the week On Thursdays my goal is to make 85 Do I meet that goal 70 of the time 3 …