# UNT DSCI 3710 - Practice Exam_1_with Keys (8 pages)

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## Practice Exam_1_with Keys

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- Pages:
- 8
- School:
- University of North Texas
- Course:
- Dsci 3710 - Business Statistics

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Practice Exam 2018 Use the information given in the following paragraph to answer the four questions that follow The Dallas Food Bureau has received several complaints that a sugar company is underfilling its five pound bags of sugar The Bureau randomly selects 1500 bags of sugar and determines the weight of each bag The sample average weight of the bags is 4 90 pounds Assume the population standard deviation is known to be 0 2 pounds At the 0 01 level of significance is there sufficient evidence that the bags are underfilled 1 What is the null hypothesis for testing whether the bags are underfilled A Ho 4 9 B Ho 5 C Ho 5 D Ho 5 E Ho 4 9 2 What is the rejection region for testing at the 0 01 level of significance whether the bags are underfilled A Z 1 645 B Z 2 04 C Z 2 58 D Z 2 33 E Z 1 96 3 Assuming the calculated value of the test statistic is 19 36 what is the conclusion of testing at the 0 01 level of significance A Reject Ha There is evidence that the bags are not underfilled B Reject Ho There is sufficient evidence that the bags are underfilled C Reject Ho That the bags are underfilled is not supported D Fail to reject Ho There is insufficient evidence to support that the bags are not underfilled E Fail to reject Ho The bags are not underfilled is supported 4 Assuming the calculated value of the test statistic was 19 36 which of the following ranges would best describe the p value for the test A p 0 1 B 0 05 p 0 10 C 0 025 p 0 05 D 0 01 p 0 025 E p 0 01 1 Use the information given in the following paragraph to answer the four questions that follow Golden Leaves Investment Inc has a large staff of sales agents nationwide Senior management of the company believe that 75 of their agents meet their annual sales goals by the end of the November of each year To investigate this they randomly select 250 agents and examined their sales records at the end of the November of the current year 180 of the 250 agents surveyed had already met their annual sales goals The senior management s claim is to be tested at 10 significance level 5 What are the null and alternative hypotheses for this test A Ho p 0 72 Ha p 0 72 B Ho p 0 75 Ha p 0 75 C Ho p 0 72 Ha p 0 72 D Ho p 0 75 Ha p 0 75 E Ho p 0 72 Ha p 0 72 6 The decision rule in this case will be to reject Ho if the value of the computed test statistic is A 1 645 or 1 645 B 2 04 C 1 28 or 1 28 D 1 28 E 1 96 7 What is the calculated observed value of the test statistic A 1 10 B 0 09 C 0 09 D 1 10 E 2 56 8 Assume the calculated test statistic is 2 56 What conclusion can be drawn A Reject Ha There is sufficient evidence to support the senior management s claim B Reject Ho The senior management s belief is not supported C Reject Ho The senior management s claim is supported D Fail to reject Ho Evidence supports the senior management s claim E Fail to reject Ho The senior management s claim is not supported 2 Use the information given in the following paragraph to answer four questions that follow A small cinema in Denton believes that a movie that is considered a comedy will draw a larger crowd on average than a movie that is a drama To test this belief the cinema randomly selects several movies that are classified as comedies and several movies that are classified as dramas and determines the tickets sold The following results are obtained with Excel assuming equal variances at a significance level of 0 05 n 1 Comedy Drama 7 9 2 8 5 3 4 5 6 7 8 9 10 11 12 5 9 25 12 8 15 7 6 18 7 6 8 12 21 14 8 7 6 8 9 t Test Two Sample Assuming Equal Variances Mean Variance Observations Pooled Variance Hypothesized Mean Difference df t Stat P T t one tail t Critical one tail P T t two tail t Critical two tail Variable Variable 1 2 10 58333 9 416667 35 53788 19 7197 12 12 xxx 0 xxx 0 543678 0 296065 1 717144 0 592131 2 073873 9 What is the Null hypothesis for this test A H0 Comedy Drama B H0 Comedy Drama C H0 Comedy Drama D H0 Comedy Drama E H0 Comedy Drama 10 What is the Pooled Variance A 13 34 B 27 63 C 10 34 D 1 80 E 0 45 11 How many degrees of freedom should be used for this t test A 24 B 22 C 20 D 12 E 11 12 Which one of the following would best describe the p value of the test A 0 001 p 0 01 B 0 01 p 0 025 C 0 025 p 0 05 D 0 05 p 0 1 E p 0 1 3 Use the information given in the paragraph below to answer the five questions that follow A director of UNT training center has learned three different methods for teaching a student to type She is interested in determining if there is a difference in the average typing speeds for students who are taught to type using each of the three methods She randomly selects 30 newly enrolled students and then randomly assigns 10 students to learn to type by each of training methods At the end of the course she examines the number of correct words per minute for all students ANOVA Single Factor SUMMARY Groups Method 1 Method 2 Method 3 Count Sum 10 468 10 521 10 565 ANOVA Source of Variation Between Groups Within Groups SS 471 8 627 Total Average Variance 46 8 20 84444 52 1 21 87778 56 5 26 94444 df MS 27 23 22222 F 29 13 The correct null hypothesis to test for any difference among methods is A Ho All true mean typing speeds differ so efficacies of methods differ from each other B Ho All true mean typing speeds are same equal C Ho Several of the true mean typing speeds differ from each other D Ho Mean typing speed for Group 3 is less than that for the other groups E Ho Not all true mean typing speeds are equal 14 The critical value of the test statistic for the above ANOVA at the 5 level of significance is approximately A 1 92 B 1 27 C 2 90 D 3 35 E 2 45 4 15 What is the Computed value of the test statistic for this ANOVA test A 49 52 B 2 31 C 10 16 …

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