Identify the choice that best completes the statement or answers the question. ____ 1. A survey conducted by Black Flag asked whether or not the action of a certain type of roach disk was effective in killing roaches. 79% of the respondents agreed that the roach disk was effective. The number 79% is a a. parameter. c. statistic. b. population. d. sample. ____ 2. A CBS News/New York Times opinion poll asked 1,190 adults whether they would prefer balancing the Federal budget over cutting taxes; 59% of those asked said "Yes." Suppose that in fact 62% of all adults favor balancing the budget over cutting taxes. The number 62% is... a. is evidence of bias. c. is a statistic. b. is a parameter. d. is a sampling distribution. ____ 3. A CBS News/New York Times opinion poll asked 1,190 adults whether they would prefer balancing the Federal budget over cutting taxes; 59% of those asked said "Yes." Suppose that in fact 62% of all adults favor balancing the budget over cutting taxes. If you take a large number of SRSs of size 1,190, the sample proportions who favor balancing the budget will vary. Some will be lower than 62% and some will be higher, but the average sample result will be very close to 62%. This fact is called a. low bias. c. high variability. b. small margin of error. d. large bias. ____ 4. A 95% confidence interval for the mean of a population is computed from a random sample and found to be 9 3. We may conclude that a. there is a 95% probability that is between 6 and 12. b. 95% of values sampled are between 6 and 12. c. if we took many, many additional random samples and from each computed a 95% confidence interval for , approximately 95% of these intervals would contain . d. there is a 95% probability that the true mean is 9 and a 95% chance that the true margin of error is 3. e. all of the above are true. ____ 5. If we take many simple random samples from the same population, we expect a. the variability of sample mean the sampling distribution to increase b. the variability of sample mean the sampling distribution to dicrease c. a different value of the parameter for each sample d. a problem with voluntary response ____ 6. If we took a SRS of 1700 people from California (population 34 million) and a SRS of 1000 people from Detroit (population 1 million) which sampling distribution would have the smaller standard deviation? a. Detroit, because 1000/1,000,000 is more than 1700/32,000,000. b. Detroit, because it has the smaller population. c. California, because the sample size (1700) is larger than for Detroit (1000). d. California, because it has the larger population.

7. A 2018 study of 240 randomly-selected residents of a subtropical resort city with 82,000 residents found that 5.4% of them had been exposed to the mosquito-borne virus that causes Dengue fever. Suppose the actual percentage of people in the city who have been exposed to the virus is 3%. Let = the proportion of residents who have been exposed in a random sample of 240, The mean of (or p) is a. 0.03. c. 7.2. b. 0.054. d. 13. ____ 8. A 2018 study of 240 randomly-selected residents of a subtropical resort city with 82,000 residents found that 5.4% of them had been exposed to the mosquito-borne virus that causes Dengue fever. Suppose the actual percentage of people in the city who have been exposed to the virus is 3%. Let = the proportion of residents who have been exposed in a random sample of 240, The standard deviation of (or p) is approximately. (Hint! Here you actually know the proportion in the population - use that! If you did not have the population proportion, use the next best thing or the sample proportion) a. 0.000121. c. 0.0110. b. 0.00187. d. 2.643. ____ 9. A 2008 Gallup poll found that 47% of adults 18 years old or older in the United States felt that a third political party is needed to represent the American people. In the description of methods, the poll takers said: "For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is 3 percentage points.". The term "95% confidence" means we can be a. sure that between 44% and 50% of all Americans think we should have a third party. b. 95% confident that 47% of all Americans think we should have a third party. c. 95% confident that between 44% and 50% of all Americans think we should have a third party. d. 95% confident that between 44% and 50% of the people interviewed think we should have a third party. ____ 10. A 2008 Gallup poll found that 47% of adults 18 years old or older in the United States felt that a third political party is needed to represent the American people. In the description of methods, the poll takers said: "For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is 3 percentage points." Among the poll respondents who identified their current party affiliation as "independent," 63% agreed that we need a third political party. The margin of error for this result is (Hint! Think of the sample size of the subgroup!) a. less than 3%, because only some of the people in the sample were independents, so the sample size is smaller. b. greater than 3%, because only some of the people in the sample were independents, so the sample size is smaller. c. equal to 3%, because this result comes from the same sample survey. d. less than 3%, because only some of the population are independents, so it's easier to estimate facts about them. 11. The critical values 2 for 95% confidence interval for a variance of a sample of 19 are a. 8.907 and 32.852 b. 8.231 and 31.526 c. 10.117 d. 9.390 ____ 12. The critical value used to construct a confidence interval for a proportion depends upon a. The size of the sample and the sample proportion. b. The confidence level being used and the size of the sample. c. Only on the confidence level. d. Only on the sample size. ____ 13. Which of the following sources of error is included in the margin of error a. chance variation in choosing a random sample. b. undercoverage. c. some of the subjects did not understand the questions. d. voluntary response. ____ 14. A quality control inspector is testing microprocessor chips made during a single day by a new machine to determine the proportion of defective chips. She selects an SRS of 80 chips from the 3000 chips produced by the machine on that day. It turns out that 6 of the chips are defective. Which of the following conditions for constructing a confidence interval for the proportion of defective chips has been violated? a. np 10andn1p 10 b. An SRS has been taken from the population of interest. c. The population is at least 10 times the size of the sample. d. The population is approximately Normally distributed. ____ 15. You are told that the proportion p of those who answered "yes" to a poll about internet use is p = 0.70, and the standard error SEp of the proportion is 0.0459. The sample size was... a. is 50. c. is 100. b. is 99. d. is 200. ____ 16. A newspaper conducted a statewide survey concerning the 2008 race for state senator. The newspaper took a random sample (assume it is an SRS) of 1200 registered voters and found that 620 would vote for the Republican candidate. Let p represent the proportion of registered voters in the state that would vote for the Republican candidate. A 90% confidence interval for p is a. 0.517 0.014. c. 0.517 0.024. b. 0.517 0.022. d. 0.517 0.028. ____ 17. After a college's football team once again lost a football game to the college's arch rival, the team wanted to know the variability in their scores. This season they played 14 games and the standard deviation so far is 7.2 points. A 98% confidence interval for 2 is a. 23.1 2 144.6 c. 24.3 2 164.1 b. 26.2 2 176.7 d. 3.4 2 22.8 18. A sociologist is studying the effect of having children within the first two years of marriage on the divorce rate. Using hospital birth records, she selects a random sample of 200 couples that had a child within the first two years of marriage. Following up on these couples, she finds that 80 couples are divorced within five years. A 90% confidence interval for the proportion p of all couples that had a child within the first two years of marriage and are divorced within five years is a. 0.40 0.004. c. 0.40 0.044. b. 0.40 0.035. d. 0.40 0.057. ____ 19. Using the same sample statistics, you calculate a 95% t-interval for a population mean and a 95% z-interval for a population mean. Which interval has a larger margin of error? a. The t-interval's margin of error is larger. b. The z-interval's margin of error is larger. c. The two intervals have the same margin of error. d. Which interval has the larger margin or error depends on the degrees of freedom for the z-interval. ____ 20. Which of the following confidence intervals has the largest critical value? a. A 95% z-interval b. A 95% t-interval with 1 degree of freedom c. A 95% t-interval with 10 degrees of freedom d. A 90% t-interval with 1 degree of freedom ____ 21. What is the critical value t* for a 90% confidence interval when n = 15? a. 1.645 c. 1.761 b. 1.753 d. 1.960 ____ 22. What is the critical value t* for a 99% confidence interval when n = 20? a. 2.086 c. 2.845 b. 2.861 d. 2.576 ____ 23. What proportion of scores in a t-distribution with 6 degrees of freedom are above t = 2.447? a. 0.90 c. 0.05 b. 0.10 d. 0.025 ____ 24. The heights (in inches) of males in the United States are believed to be Normally distributed with mean . The average height of a random sample of twenty-five American adult males is found to be x = 69.72 inches and the standard deviation of the twenty-five heights is found to be s = 4.15. The standard error of x is a. 0.17. c. 0.83. b. 0.69. d. 1.856. ____ 25. Scores on the SAT Mathematics test (SAT-M) are believed to be Normally distributed with mean . The scores of a random sample of three students who recently took the exam are 550, 620, and 480. A 95% confidence interval for based on these data is a. 550.00 401.11. c. 550.00 142.00. b. 550.00 173.88. d. 550.00 128.58. 26. In checking conditions for constructing confidence intervals for a population mean, it's important to plot the distribution of sample data. Below are dot plots describing samples from three different populations. For which of the three samples would it be safe to construct a t-interval?

a. Plot X only c. Plot Z only b. Plot Y only d. Plots Y and Z ____ 27. A fast food restaurant chain is adding a new restaurant and conducted a study to determine the percentage of people who prefer to use the drive-thru during their lunch break. The proportion from that study was 64%. At the 90% confidence level, how large should the sample be to estimate the true proportion of those people with the margin of error within 2 percentage points from the population proportion? a. 36 c. 1,568 b. 1.65 d. 1,569 ____ 28. In a sample of 500 commuter students, the mean time spent commuting daily was 2 hours. The population standard deviation is 15 minutes (or 0.25 hour). Find the 95% confidence interval for the population average. a. 1.96 c. 1.51 2.49 b. 1.8 2.2 d. 1.1 2.1