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UNT DSCI 3710 - DSCI 3710 Exam1Fall2010Key_VerA

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1 COURSE: DSCI 3710 Print Name: Exam 1 Ver. A Signature: Key Fall 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 75 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 following paragraph for the next five questions. The U.S. Census Bureau conducts annual surveys to obtain information on the percentage of the voting-age population that is registered to vote. Suppose that 724 employed persons and 596 unemployed persons are independently and randomly selected, and that 465 of the employed persons and 306 of the unemployed persons have registered to vote. Can we conclude that the percentage of employed workers ()p1, who have registered to vote, exceeds the percentage of unemployed workers ()p2, who have registered to vote? Use a significance level of = 0.05 for the test. The KPK Macro output is shown below. Z Test for Two Proportions Employed Unemployed Sample Proportion 0.642265 xxxxxxxx Number of Observations 724 596 Ho:xxxxxxx Ha:xxxxxx Z* 4.726338 P[Z  Z*] 0.000001 Z Critical,  = 0.05 xxxxxxx 95% CI for p1 ‐ p2 0.075610 to 0.182075 1. What is the null hypothesis for the test? A. p1 < p2 B. p1 ≠ p2 C. p1 > p2 D. p1 < p2 * E. p1 = p2 2. What is the point estimate of the proportion of unemployed persons who have registered to vote ? A. 0.642 B. 0.584 C. 0.075 D. 0.182 E. 0.513* 3. What is the critical (table) value for the test statistic? A. 1.282 B. 1.33 C. 1.645* D. 1.96 E. 2.333 4. What is the estimated pooled proportion ( p ) of voting-age population registered to vote? A. 0.642 B. 0.584* C. 0.075 D. 0.182 E. 0.513 5. Let us assume instead that we were interested in testing whether there was a difference in the percentage of employed workers ()p1, who have registered to vote versus the percentage of unemployed workers ()p2, who have registered to vote. Then, based upon the 95% confidence interval as given in the KPK output, what would be the conclusion of our hypothesis test and the reason for the conclusion? A. Reject the null hypothesis because the hypothesized difference is contained in the confidence interval B. Fail to reject the null hypothesis because the hypothesized difference is contained in the confidence interval C. Reject the null hypothesis because the hypothesized difference is not contained in the confidence interval* D. Fail to reject the null hypothesis because the hypothesized difference is not contained in the confidence interval E. Reject the null hypothesis because the hypothesized difference is the confidence interval Use the information given in the following paragraph to answer the next three questions. Using traditional methods it takes 90 hours to receive a basic flying license. A new license training method using Computer Aided Instruction (CAI) has been proposed. A researcher used the technique on 50 students and observed that they had a mean of 88 hours. Assume the standard deviation is known to be 6 hours. Is there evidence at the 0.05 level that the technique performs differently than the traditional method? 6. What are the null hypothesis and alternative hypothesis for this test? A. Ho: µ = 88 Ha: µ ≠ 88 B. Ho: µ ≥ 88 Ha: µ < 88 C. Ho: µ = 90 Ha: µ ≠ 90* D. Ho: µ < 90 Ha: µ > 90 E. Ho: µ = 90 Ha: µ < 90 7. What is the absolute critical (table) value of the test statistic? A. 1.645 B. 1.96* C. 2.33 D. 3.69 E. 2.574 8. Assuming the calculated value of the test statistic is -2.36, what are the decision and conclusion of the test? A. Fail to reject the null hypothesis, conclude there is overwhelming evidence that the technique performs differently than the traditional method B. Fail to reject the null hypothesis, conclude there is insufficient evidence that the technique performs differently than the traditional method. C. Reject the null hypothesis, conclude there is evidence that the technique performs differently than the traditional method.* D. Fail to reject the null hypothesis, conclude there is evidence that the technique performs differently than the traditional method. E. Reject the null hypothesis, conclude there is insufficient evidence that the technique performs differently than the traditional method. Use the information given in the paragraph below to answer the next three questions. The mayor of a town believes that more than 40% of the residents favor annexation of a new community. A sample of 800 voters showed that 43% of the residents favored annexation. Is there sufficient evidence at the 0.02 level to support the mayor's claim? 9. What is the alternative hypothesis for this test? A. Ha: p  0.43 B. Ha:  > 0.4 C. Ha:   0.4 D. Ha: p > 0.4* E. Ha: p < 0.4 10. 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. 11. What is the observed level of significance if the calculated test statistic is assumed to be 1.73? A. 0.334 B. 0.0209 C. 0.02 D. 0.126 E. 0.0418*5 Use the information below to answer the next three questions. Two teaching methods and their effects on science test scores are being reviewed. A random sample of 18 students was taught in traditional lab sessions and a random sample of 13 students was taught using interactive simulation software. Do the results displayed in the output below support the claim that the


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