1. What Z-value is associated with a 95% confidence interval?A. 1.28B. 1.65C. 1.96D. 2.58

2. Which of the following is NOT a property of the t distribution?A. It is symmetric.B. Its exact shape (i.e., spread) is characterized by the degrees of freedom.C. As the sample size grows, it gradually approaches the normal distribution.D. All of the above are properties of the t distribution.

3. A 95% confidence interval for the mean can be interpreted to mean which of the following?A. If all possible samples are taken and confidence intervals calculated, 95% of those intervals would include the true population mean somewhere in their interval.B. You can be 95% confident that you have selected a sample whose interval includes the population mean.C. Both answers #1 and #2 are correct.D. Neither answer #1 nor #2 is correct.

4. Two random samples have sizes of n=49 and n=36 respectively. Which of the following is true for a 95% confidence interval?A. The sample of n=36 has a greater degree of confidence.B. The sample of n=49 has a greater degree of confidence.C. The confidence interval for the sample of n=49 is narrower.D. The confidence interval for the sample of n=49 is wider.

5. The Z value selected for constructing a given confidence interval is also called what?A. The Z value is also called the critical value.B. The Z value is also called the student value.C. The Z value is also called the confidence value.

D. The Z value is often called the error value.

6. A sample of 50 students was taken from the local university. These students spent an average of $170 on books this semester, with a standard deviation of $25.50. Which of the following could you say with 95% confidence was the average spent on books by these 50 students?A. $170 plus or minus $3.46B. $170 plus or minus $5.95C. $170 plus or minus $8.42D. None of these is correct.

7. A random sample of 72 statistics students was taken to estimate the proportion of students who also were in the Math Club. The 90% confidence interval was 0.438 to 0.642. Using this information, what size sample would be necessary to estimateA. 105B. 150C. 420D. 597

8. The following sample was taken from a normally distributed population: 15, 22, 10, 15, 11, 17, and 8. Calculate the 95% confidence interval for this sample.A. 14 plus or minus 6.52B. 14 plus or minus 10.35C. 14 plus or minus 8.97D. 14 plus or minus 4.409. The width of a confidence interval for a proportion will beA. narrower for 99% confidence than for 95% confidence.B. wider for a sample of size 100 than for a sample of size 50.C. wider for 90% confidence than for 95% confidence.D. wider when the sample proportion is 0.50 than when the sample proportion is 0.20.

10. A sample size of 200 light bulbs was tested and found that 11 were defective. What is the 95% confidence interval around this sample proportion?A. 0.055 plus or minus 0.032B. 0.055 plus or minus 0.009C. 0.055 plus or minus 0.044D. 0.055 plus or minus 0.018

11. The sample mean is an unbiased point estimator ofA. the population variance.B. the population mean.C. the population proportion.D. None of the above

12. An economist is interested in studying the incomes of consumers in a particular region. The population standard deviation is known to be $1,000. What sample size would the economist need to use for a 95% confiden7ce interval if the width of the interval should not be more than $100?A. 20B. 40C. 385D. 1537

13. The confidence interval for the difference between two population means that are normally distributed where the population variances are unknown but assumed equal rely on A. the average sample variance.B. the estimated sample variance.C. Satterthwaite's approximation.D. the pooled sample variance.

14. In a random sample of 400 Georgia residents, 272 indicated they were home owners. In another random sample of 600 Florida residents, 390 were home owners. What is the 99%confidence interval for the difference between the proportions?A. 0.030 plus or minus 0.016B. 0.030 plus or minus 0.035C. 0.030 plus or minus 0.051D. 0.030 plus or minus 0.07715. If you were running a small sample (e.g., n=24) two-sided test at level of significance .05, then the critical t-value would be _________.A. 1.711B. 2.069C. 1.714D. 1.96

16. A student claims that he can correctly identify whether a person is a business major or an agriculture major by the way the person dresses. Suppose in actuality that he can correctly identify a business major 87% of the time, while 16% of the time he mistakenly identifies an agriculture major as a business major. Presented with one person and asked to identify the major of this person (who is either a business or agriculture major), he considers this to be a hypothesis test with the null hypothesis being that the person is a business major and the alternative that the person is an agriculture major. What would be a Type I error? A. Saying that the person is an agriculture major when in fact the person is a business major.B. Saying that the person is a business major when in fact the person is a business major.C. Saying that the person is a business major when in fact the person is an agriculture major.D. Saying that the person is an agriculture major when in fact the person is an agriculture major.

17. The probability of rejecting the null hypothesis that is true isA. known as the confidence level.B. p-value.C. power of the test.D. significance level.

18. A small business college claims that their average class size is equal to 35 students. This claim is being tested with alpha equal to 0.05 using the following sample of class sizes: 42, 28, 36, 47, 35, 41, 33, 30, 39, and 48. Assume class sizes are normally distributed. What is the test statistic and what conclusions will be drawn?A. Since the test statistics equals 1.36, we reject the null hypothesis and conclude that class size does not equal 35 students.B. Since the test statistics equals 1.36, we fail to reject the null hypothesis and conclude that class size does equal 35 students.C. Since the test statistics equals 2.26, we reject the null hypothesis and conclude that class size does not equal 35 students.D. Since the test statistics equals 2.26, we fail to reject the null hypothesis and conclude that class size does equal 35 students.

19. Each of the following statements is true except:A. The level of significance of a hypothesis test is called alphaB. The probability of making a Type II error is called beta.C. The probability of rejecting a null hypothesis when it is true is called alpha D. The probability of making a Type I error is called beta.

20. Test at the level of significance of 0.01 that 55% of season ticket holders plan to buy season tickets the next year. The local newspaper reports that the proportion of those season ticket holders who buy tickets next year is not equal to 55%. A random sample of 400 season ticket holders reveals that 228 will buy season tickets next year. What decision should be made regarding the null hypothesis?A. reject itB. none of the aboveC. do not reject itD. cannot accept or reject it

21. A local eat-in pizza restaurant wants to investigate the possibility of starting to deliver pizzas. The owner of the store has determined the home delivery will be successful if the average time spent on the deliveries does not exceed 38 minutes. The owner has randomly selected 15 customers and has delivered pizzas to their homes. What assumption is necessary for the test above to be valid?A. The population variance must equal the population mean.B. None of these assumptions are necessary.C. The population of paired differences must be normalD. The population of delivery times must have a normal distribution.

22. The alternative hypothesis for the difference between two means is "mu1-mu2 is not equal 0".For this test, the test statistic, z is 3.09. What is the p-value for the test?A. 0.05B. 0.001C. 0.002D. 0.499

23. A study by a corporation revealed that the mean weekly salary for managers in department A was $1,200 with a standard deviation of $100 (sample size = 64) while the mean weekly salary for managers in department B was $1350 and a standard deviation of $150 ( sample size = 81 )The hypothesis test is to be conducted at the level of significance of 5%. The critical region for this test is A. z < -1.645B. z > 1.96 or z < -1.96C. -1.96 < z < 1.96D. z >1.645

24. Which of the following statements is not correct for the F distribution?A. Degrees of freedom for the numerator can exceed degrees of freedom for the denominator or be smaller than or equal to the degrees of freedom for the denominator.B. Degrees of freedom for the denominator are always smaller than the degrees of freedom for the numerator.C. The F distribution is used to compare two population variances.D. The exact shape of the F distribution depends upon the degrees of freedom associated with the two samples.

25. A researcher wanted to investigate which of two newly developed automobile engine oils (A and B) is better at prolonging the life of the engine. Since there are a variety of automobile engines that are used in today's cars, 20 different engine types were randomly selected and were tested using each of the two engine oils. The number of hours of continuous use before engine breakdown was recorded for each engine oil. Based on the information provided, what type of analysis will yield the most useful information?A. Matched pairs comparison of population proportionsB. Matched pairs comparison of population meansC. Independent samples comparison of population meansD. Independent samples comparison of population proportions26. I would like to test the null hypothesis that the population mean is 50 versus the alternative that it is not 50. My sample size is 6, and the sample mean is 38 with sample standard deviation of 16. At = 0.05, I should:A) strongly reject the null hypothesisB) mildly reject the null hypothesisC) fail to reject the null hypothesisD) accept the alternative hypothesisE) there is insufficient information to determine27. The proportion of defective items is not allowed to be over 15%. A buyer wants to test whether the proportion of defectives exceeds the allowable limit. The buyer takes a random sample of 100 items and finds that 19 are defective. State the null and alternative hypotheses for this test.A) H0: p .15, H1: p > .15B) H0: p < .15, H1: p .15C) H0: p = .15, H1: p .15D) H0: p < .15, H1: p > .15E) none of the above

28. A manufacturer claims that his tires last at least 40,000 miles. A test on 25 tires reveals that the mean life of a tire is 39,750 miles, with a standard deviation of 387 miles. Compute the test statistic.A) t = -0.65B) t = 3.23C) t = -3.23D) t = 0.65E) none of the above

29. Given a p-value of 0.065, and using the customary = 5%, the conclusion should be:A) accept the null hypothesisB) reject the null hypothesisC) not enough information to determine30. A random sample of 36 items gave a sample mean of 48 and a sample standard deviation of 12. Compute the p-value to test whether or not the population mean is equal to 50.A) 0.3413B) -0.4772C) 0.1587D) 0.6826E) 0.317431. I want to conduct a statistical test of whether or not the population mean is 70. My sample mean is 71, my sample standard deviation is 5, and my sample size is 100. The result is:A) not significant B) significantC) very significantD) cant tell

32. When testing for the equality of two population means, using = 0.05 with n1 = 12 and n2 =10, the critical points are:a) +2.704 and 2.704b) +1.96 and 1.96c) +2.086 and 2.086d) +1.645 and 1.645e) none of the aboveUse the following to answer questions 6, 7, 8:A company made a major change in its advertising theme this year and is interested in knowing whether there is any significant increase in sales over last year. The following data is the sales in thousands for different stores over the country, and has been adjusted for inflation. Take the difference as (current years sales last years sales).StoreLast Years SalesCurrent Years Sales

1183206

2406528

3388678

4694601

5274258

6137170

73331

814231468

33. State the null and alternative hypotheses to test the hypothesis that the change in advertising has increased sales.a) H0: D > 0, H1: D 0b) H0: D 0, H1: D > 0c) H0: D 0, H1: D < 0d) H0: D = 0, H1: D > 0e) none of the above34. Find the critical value to test the hypothesis that the change in advertising has increased sales, using = 0.05.a) +1.645b) +1.96c) +2.365d) +1.895e) none of the above35. Construct a 95% confidence interval for the average change in sales.a) 50.25 (2.365) (40.385)b) 50.25 (1.96) (40.385)c) 50.25 (1.895) (40.385)d) 50.25 (2.306) (40.385)e) none of the aboveUse the following to answer questions 9, 10:A programmer has written a software package that points out errors in programs. Previously, this was done manually. The mean number of errors the software picket out of 100 different programs was 15, with a standard deviation of 8.2. The mean number of errors picked out manually, out of 100 programs, was 13, with a standard deviation of 4.9. We want to test whether there is evidence that this software picks out more errors than checking manually does. Assume that the software is population 1 and manual checking is population 2.36. State the null and alternative hypotheses to test whether this software does pick out more errors.a) H0: 1 - 2 0, H1: 1 - 2 > 0b) H0: 1 - 2 = 0, H1: 1 - 2 0c) H0: 1 - 2 0, H1: 1 - 2 < 0d) H0: 1 - 2 > 0, H1: 1 - 2 0e) none of the above37. Find the critical points to test whether this software does find more errors, at = 0.05.a) +1.96b) +1.645c) +1.282d) +2.575e) +2.3338. When testing for the equality of two population proportions, the F distribution is:a) sometimes appropriateb) never appropriatec) only appropriate if both sample sizes are less than 30d) only appropriate if at least one sample is at least 30e) used when the two variances are not equal39. Calculate the pooled variance for the following sample data.

Sample meanSample VarianceSample Size

401012

301215

a) 3.33b) 124.64c) 11.12d) 34.4e) none of the above40. Compute the p-value for a two-tailed test of the difference in two means, with both sample sizes at least 30, if the test statistic is z = 2.50. 0.0124

41. A survey was conducted to see if the proportion of men and women liking this brand of jeans differed. In a sample of 100 men and 90 women, 62 of the men liked the jeans, and 66 of the women liked the jeans. Construct a 95% confidence interval for the difference in the proportion of men and women liking these jeans.CI =

42. A Type II error occurs whenA. We accept a false null hypothesis. B. We reject a true alternate hypothesis.C. We reject a false null hypothesis. D. None of the above.

43. If a hypothesis test leads to the rejection of the null hypothesis A. a Type II error is always committed B a Type I error is always committed C. a Type I error may have been committed D. a Type II error may have been committed

44. How many Kleenex should the Kimberly Clark Corporation package of tissues contain? Researchers determined that 60 tissues is the average number of tissues used during a cold. Suppose a random sample of 10000 Kleenex users yielded the following data on the number of tissues used during a cold: Give the null and alternative hypothesis to determine if the number of tissues used during a cold is less than 60. A. H0: = 60 vs. H1: > 60B. H0: = 60 vs. H1: < 60C. H0: = 60 vs. H1: 60D. H0: > 60 vs. H1: