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STATS Exam Questions

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Question;P3 ? where applicable, readings from tables must be used.1.The quality-control manager at a light bulb factory needs to determine whether the mean life of a large shipment of light bulbs is equal to 375 hours. The population standard deviation is 100 hours. A random sample of 64 light bulbs indicates a sample mean life of 350 hours.a) At the 0.05 level of significance, is there evidence that the mean life is different from 375 hours?b) Compute the p-value and interpret its meaning.c) Construct a 95% confidence interval estimate of the pupulation mean life of the light bulbs.d) Compare the reuslts of (a) and (c). What conclusions do you reach?2. If, in a sample of n = 16 selected from a normal population, X? = 56 and S = 12, what is the value of tSTAT if you are testing the null hypothesis H0:? = 50?3. In problem 2 above, how many degrees of freedom are there in the t- test?4. In problems 2 and 3, what are the critical values of t if the level of significance,? is 0.05 and the alternative hypothesis, H1, is?? 50?5. In problem 2, 3 and 4, what is your statistical decision if the alternative hypothesis, H1 is?? 50?6. In a training process, the average time taken is 6.4 hours. Eight employees were trained using a new method and they had an average training time of 6.2 hours and a standard deviation of 1.1 hours. Use? = 0.01 to determine if the new process reduced the training time.Question 1In testing for differences between the means of two related populations, the null hypothesis isH0:? D = 2.H0:? D = 0.H0:? D 0.Question 2A powerful women's group has claimed that men and women differ in attitudes about sexual discrimination. A group of 50 men (group 1) and 40 women (group 2) were asked if they thought sexual discrimination is a problem in the United States. Of those sampled, 11 of the men and 19 of the women did believe that sexual discrimination is a problem. Find the value of the test statistic.Z = -2.55Z = -0.85Z = -1.05Z = -1.20Question 3When testing H0:? 1 -? 2? 0 versus H1:? 1 -? 2 > 0, the observed value of the Z-score was found to be -2.13. The p-value for this test would be0.0166.0.0332.0.9668.0.9834.Question 4Given the following information, calculate the degrees of freedom that should be used in the pooled-variance t test.s12 = 4 s22 = 6n1 = 16 n2 = 25df = 41df = 39df = 16df = 25Question 5TABLE 10-1Are Japanese managers more motivated than American managers? A randomly selected group of each were administered the Sarnoff Survey of Attitudes Toward Life (SSATL), which measures motivation for upward mobility. The SSATL scores are summarized below.American JapaneseSample size 211 100Mean SSATL Score 65.75 79.83Population Std. Dev. 11.07 6.41Referring to Table 10-1, give the null and alternative hypotheses to determine if the mean SSATL score of Japanese managers differs from the mean SSATL score of American managers.H0:? A -? J? 0 versus H1:? A -? J 0H0:? A -? J = 0 versus H1:? A -? J? 0H0: X? A - X? J? 0 versus H1: X? A - X? J? 0Question 6TABLE 10-5To test the effectiveness of a business school preparation course, 8 students took a general business test before and after the course. The results are given below.Student Exam scoreBefore Course (1) Exam ScoreAfter course (2)1 530 6702 690 7703 910 10004 700 7105 450 5506 820 8707 820 7708 630 610Referring to Table 10-5, what is the critical value for testing at the 5% level of significance whether the business school preparation course is effective in improving exam scores?2.3652.1451.7611.895Question 7The t test for the difference between the means of 2 independent populations assumes that the respectivesample sizes are equal.sample variances are equal.populations are approximately normal.All of these.Question 8TABLE 10-4A real estate company is interested in testing whether, on average, families in Gotham have been living in their current homes for less time than families in Metropolis have. Assume that the two population variances are equal. A random sample of 100 families from Gotham and a random sample of 150 families in Metropolis yield the following data on length of residence in current homes.Gotham: X?G = 35 months, SG2 = 900 Metropolis: X?M = 50 months, SM2 =1050Referring to Table 10-4, what is the standardized value of the estimate of the mean of the sampling distribution of the difference between sample means?-8.75-3.69-2.33-1.96Question 9TABLE 10-4A real estate company is interested in testing whether, on average, families in Gotham have been living in their current homes for less time than families in Metropolis have. Assume that the two population variances are equal. A random sample of 100 families from Gotham and a random sample of 150 families in Metropolis yield the following data on length of residence in current homes.Gotham: X?G = 35 months, SG2 = 900 Metropolis: X?M = 50 months, SM2 =1050Referring to Table 10-4, what is the estimated standard error of the difference between the 2 sample means?4.065.618.0116.00Question 10Given the following information, calculate sp2, the pooled sample variance that should be used in the pooled-variance t test.s12 = 4 s22 = 6n1 = 16 n2 = 25sp2 = 6.00sp2 = 5.00sp2 = 5.23sp2 = 4.00Question 11If we are testing for the difference between the means of 2 related populations with samples of n1 = 20 and n2 = 20, the number of degrees of freedom is equal to39.38.19.18.Question 12In testing for differences between the means of two independent populations, the null hypothesis is:H0:? 1 -? 2 = 2.H0:?1 -? 2 = 0.H0:? 1 -? 2 > 0.H0:? 1 -? 2? malesH1:? females

 

Paper#61532 | Written in 18-Jul-2015

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