1 COURSE: DSCI 3710 Print Name: Exam 1 Signature: Summer 1 2010 Student ID#: INSTRUCTIONS: • Please print your name and student ID number on this exam. Also, put your signature on this exam. • On your scantron PRINT your name and exam version. • You have 105 minutes to complete this exam. The exam is open book, open notes, and open mind. You may use any type of hand calculator but please show all your work on the exam and mark all answers on the scantron. Usage of cell phones, digital cameras, PDAs, and other communication devices is prohibited. • Please DO NOT pull this exam apart. When you have completed the exam, please turn your scantron and exam booklet into your instructor, at the front desk. • Good luck and we wish you well on the exam. Note: Whenever question(s) are connected you may be asked to assume a result (given a value) as an answer for the previous question but this result (value) may or may not be correct. The procedure is set in place to prevent you from losing points on a subsequent question because you made a mistake on some previous question/s.2 Use the information given in the following paragraph to answer next three questions. A lumber company is making 2x4s that are 11 feet long. These 2x4s are being used to make prefabricated homes. If the 2x4s are too long they must be trimmed which results in extra time and labor being expended, but if too short they can be used as is, by supplying them to a children’s toy store. A sample of 130 2x4s is made, and it is found that they averaged 11.9 feet with a standard deviation of 0.04 feet. Is there evidence, at the 0.05 significance level, that the 2x4s are too long? 1. What are the null hypothesis and alternative hypothesis for this test? A. Ho: µ = 11.9 Ha: µ ≠ 11.9 B. Ho: µ ≥ 11.9 Ha: µ < 11.9 C. Ho: µ = 11 Ha: µ ≠ 11 D. Ho: µ < 11 Ha: µ > 11 E. Ho: µ = 11 Ha: µ < 11 2. What is the absolute critical value of the test statistic? A. 1.645 B. 1.96 C. 2.33 D. 3.69 E. 2.57 3. Assuming the calculated value of the test statistic is +1.83, what are the decision and conclusion of the test? A. Fail to reject the null hypothesis, conclude there is overwhelming evidence the 2x4s are not too long. B. Fail to reject the null hypothesis, conclude there is insufficient evidence that the 2x4s are too long. C. Reject the null hypothesis, conclude there is evidence that the 2x4s are too long. D. Fail to reject the null hypothesis, conclude there is evidence the 2x4s are too long. E. Reject the null hypothesis, conclude there is insufficient evidence the 2x4s are too long.3 Use the information given below to answer the next question. The production manager in a chemical plant knows that the time for a certain product line to become stable after being stopped for machine adjustments is normally distributed. He uses a sample of 25 stoppages to determine a 95% confidence interval for the average warm-up period to be 11.3 to 19.7 minutes. The firm=s cost accountant would like to answer the following question: Is there sufficient evidence, at the 5% significance level, to indicate that the average warm-up period is different from 15 minutes? 4. What should be the decision and conclusion based on the confidence interval? A. Reject the null hypothesis, conclude that there is evidence the average warm-up period is equal to 15.5 minutes. B. Fail to reject the null hypothesis, conclude that there is sufficient evidence the average warm-up period is equal to15 minutes. C. Fail to reject the null hypothesis, conclude that there is insufficient evidence the average warm-up period is not equal to 15 minutes. D. Reject the null hypothesis, conclude that there is evidence the average warm-up period is not equal to 25 minutes. E. There is insufficient information given to decide whether the average warm-up period is equal to 15 minutes or not. Use the information given in the paragraph below to answer the next two questions. Hourly wages in a retailing industry are normally distributed with a mean believed to be $22 and a standard deviation known to be $3. A random sample of 10 workers from this industry was collected. The sample average hourly wage was $25. Test whether a peer group’s accusation of industry wages being higher than assumed, is in order? 5. What is the alternative hypothesis for this test? A. Ha: μ ≠ 22 B. Ha: μ > 22 C. Ha: μ ≠ 25 D. Ha: μ > 25 E. Ha: μ ≥ 22 6. What is the appropriate test statistic to use here? A. F B. t C. Z D. None of these. E. Any of a. through c.4 Use the information below to answer the next two questions. Coach Carlisle of the Dallas Mavericks is perplexed. The Mavericks cannot seem to consistently perform well against the Lakers. Coach Carlisle thinks the Mavericks have a clear-cut height disadvantage and comes to you for proof. You take random samples of 5 players from each team and obtain the following Excel output assuming equal variances and a 0.05 level of significance. t-Test: Two-Sample Assuming Equal Variances Lakers Mavericks Mean 83.8 76.8 Variance xxxx 16.2 Observations 5 5 Pooled Variance xxxxx Hypothesized Mean Difference 0 df xxxxx t Stat 2.336 P(T<=t) one-tail xxxxx t Critical one-tail 1.859 P(T<=t) two-tail xxxxx t Critical two-tail 2.306 7. What is the sample mean difference in heights between the two teams? A. 83.8 B. 7 C. 2.34 D. 76.8 E. 0 8. Assuming the calculated value of the test statistic is 2.0 what is the p-value? A. 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 Use the information given below to answer the next six questions. The production manager of NighKey tennis shoes wants to compare the durability of her shoes with that of ReeBuck. The production manager decides to test her belief of a difference in durability by conducting two experiments. In one experiment, she used 14 randomly selected people to wear the NighKey brand shoes and another 14 randomly selected people to wear the ReeBuck shoes, for 6 months. In a second experiment, she ensured that 14 different people wore a NighKey shoe on one foot and ReeBuck shoe on the other, for 6 months. She measured the wear of the two different brands of shoes
View Full Document
Unlocking...