Name: __________________________  Date: _____________

1.	A psychologist wants to know if adults with normal vision can be fooled by a certain optical illusion.  She recruits 50 students from her PSY 120 class and finds that 42 of them are fooled by the illusion.  The population in this study is	
A)	the 42 students who were fooled.	
B)	the 50 students who served as subjects.	
C)	all students in the PSY 120 class.	
D)	all adults with normal vision.	

Use the following to answer question 2:

A 2008 national sample survey interviewed 1,007 people age 18 and older nationwide by telephone.  One question asked was whether "on the whole would you say you are satisfied or dissatisfied with the way the nation is being governed?"

2.	The population for this sample survey appears to be	
A)	all adult residents of the U.S.	
B)	all registered voters.	
C)	the 1,007 people who were interviewed.	
D)	people who think we should have a third political party.	
E)	all U.S. citizens.	

Use the following to answer questions 3-4:

You want to know the opinions of American school teachers about establishing a national test for high school graduation.  You obtain a list of the members of the National Education Association (the largest teachers' union) and mail a questionnaire to 2500 teachers chosen at random from this list.  In all 1,347 teachers return the questionnaire.

3.	In this situation, the population is	
A)	the 1,347 teachers who mail back the questionnaire.	
B)	the 2,500 teachers to whom you mailed the questionnaire.	
C)	all members of the National Education Association.	
D)	all American school teachers.	
E)	all American school students.	

4.	The sample is	
A)	the 1,347 teachers who mail back the questionnaire.	
B)	the 2,500 teachers to whom you mailed the questionnaire.	
C)	all members of the National Education Association.	
D)	all American school teachers.	
E)	all American school students.	

Use the following to answer question 5:

The General Social Survey (GSS), conducted by the National Opinion Research Center at the University of Chicago, is a major source of data on social attitudes in the U.S.  Once each year 1500 adults are interviewed in their homes all across the country.  The subjects are asked their opinions about sex and marriage, attitudes toward women, welfare, foreign policy, and many other issues.

5.	The population for the GSS is	
A)	all adult residents of the U.S.	
B)	the University of Chicago.	
C)	the 1,500 persons interviewed.	
D)	the list of questions asked.	

6.	A Gallup Poll asked 1,002 randomly chosen adults to rate the "honesty and ethical standards" of 21 occupations.  Nurses were at the top, with 82% of the poll respondents rating them "very high" or "high."  Telemarketers were at the bottom with just 7% "very high" or "high" ratings.   The population for this poll is	
A)	all adults.	
B)	the 1,002 respondents.	
C)	people in 21 occupations.	
D)	nurses and telemarketers.	

Use the following to answer question 7:

Do doctors in managed care plans give less charity care?  Researchers chose 60 communities at random, then chose doctors at random in each community.  In all, they interviewed 10,881 doctors.  Overall, 77.3% of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview.  Doctors who received at least 85% of their practice income from managed care plans were significantly less likely than other doctors to provide charity care.

7.	The phrase "significantly less likely" means that when we compare the charity work of doctors with more than 85% of their practice in managed care with other doctors,	
A)	the difference in charity work is very large.	
B)	the difference in charity work is so large that it would rarely occur just by chance in choosing a sample.	
C)	the difference in charity work is large enough to affect doctors' income.	
D)	the difference in charity work is less than we would expect just by chance in choosing a sample.	

8.	Confounding often defeats attempts to show that one variable causes changes in another variable.  Confounding means that	
A)	this was an observational study, so cause and effect conclusions are not possible.	
B)	the effects of several variables are mixed up, so we cannot say which is causing the response.	
C)	we don't know which is the response variable and which is the explanatory variable.	
D)	we would get widely varied results if we repeated the study many times.	

Use the following to answer question 9:

Does coaching raise SAT scores?  Because many students score higher on a second try even without coaching, a study looked at an SRS of 4,200 students who took the SAT twice.  Of these, 500 had taken coaching courses between their two attempts at the SAT.  The study compared the average increase in scores (out of the total possible score of 2,400) for students who were coached with the average increase for students who were not coached.

9.	The SAT study doesn't show that coaching causes a greater increase in SAT scores.  One plausible reason is that	
A)	students who chose coaching were different (in particular, they were richer) than students who had no coaching.	
B)	4,200 students is too few to draw a conclusion.	
C)	more students were not coached than were coached.	
D)	there was no random selection.	

Use the following to answer question 10:

Does using a cell phone while driving make an accident more likely?  Researchers compared telephone company and police records to find 699 people who had cell phones and were also involved in an auto accident.  Using phone billing records, they compared cell phone use in the period of the accident with cell phone use the same period on a previous day.  Result: the risk of an accident was four times higher when using a cell phone.

10.	An example of a lurking variable that might affect the results of this study is	
A)	whether the subject had an auto accident.	
B)	whether the subject was using a cell phone.	
C)	whether the subject was talking to a passenger in the  car.	
D)	whether the subject owned a cell phone.	

Use the following to answer questions 11-12:

A sportswriter wants to know how strongly Columbus, Ohio residents support building a new stadium for the local minor league baseball team, the Columbus Clippers.  She stands outside the stadium before a game and interviews the first 25 people who enter the stadium.

11.	The population for this survey is	
A)	all residents of Columbus, Ohio.	
B)	all Clipper fans.	
C)	all people attending the game the day the survey was conducted.	
D)	the 25 people who gave the sportswriter their opinion.	
E)	all American adults.	

12.	The sample for the survey is	
A)	all residents of Columbus, Ohio.	
B)	all Clipper fans.	
C)	all people attending the game the day the survey was conducted.	
D)	the 25 people who gave the sportswriter their opinion.	
E)	the sportswriter.	

13.	An important reason for the use of randomization in designing experiments is that it tends to	
A)	reduce confounding.	
B)	allow double-blinding.	
C)	eliminate response error.	
D)	reduce the placebo effect.	

Use the following to answer questions 14-16:

A farmer wishes to determine which of two brands of baby-pig pellets, Kent or Moormans, produces better weight gains.  Two of his sows each give birth to litters of 10 pigs on the same day, so he decides to give the baby-pigs in litter A only Kent pellets, while the pigs in litter B will get only Moormans pellets.  After four weeks, the average weight gain for pigs in litter A is greater than the average weight gain for pigs in litter B.

14.	In the farmer story above, the weight of the pigs after four weeks is	
A)	a parameter.	
B)	the response variable.	
C)	the explanatory variable.	
D)	the placebo effect.	
E)	stratified.	

15.	The brand of pellets in this story is	
A)	a parameter.	
B)	the response variable.	
C)	the explanatory variable.	
D)	the placebo effect.	
E)	stratified.	

16.	The feed they get is not the only factor affecting the rate at which pigs gain weight.  Genetic differences also affect weight gain.  It is likely that the pigs in litter A are genetically different from the pigs in litter B, since the two litters have different mothers.  Since the farmer is only interested in determining which brand of pellets is better, the study suffers from	
A)	confounding.	
B)	voluntary response.	
C)	convenience sampling.	
D)	invalid measurement.	
E)	the placebo effect.	

Use the following to answer question 17:

An experiment is conducted to determine whether the caffeine in two cups of regular coffee, taken each morning before class, can improve the performance of a typical student on a statistics exam.

Suppose all students in the 8:30 section are given the treatment (two cups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before class.

17.	Unfortunately, any systematic difference between the two sections on the exam might be due to the fact that the 8:30 and 9:30 classes have different instructors. This is an example of	
A)	placebo effect.	
B)	systematic sampling.	
C)	confounding.	
D)	observational study.	
E)	stratification.	

Use the following to answer question 18:

A study compares online instruction with a standard lecture for teaching statistics.

18.	Does the study (properly designed) give good reason to think that using online instruction causes a bigger increase in statistics scores?	
A)	Yes—randomized comparative experiments give good evidence for causation	
B)	No—students at schools that use online instruction may be different from students at schools that use lectures.	
C)	Yes—a large sample will accurately represent the population.	
D)	No—students who choose to use online instruction are different from students who attend lectures.	
E)	No—random assignment means the results could just be due to chance.	

Use the following to answer question 19:

A news report says, "New research suggests that an active social life may increase resistance to respiratory infections.  In a recent study, 300 healthy volunteers were given nasal sprays of cold virus and quarantined for five days.  The volunteers were asked about relationships with spouse, children, friends, neighbors, and coworkers.  Those who had only one to three types of relationships were four times as likely to get a cold as those six or more types. The most significant factor for resisting the cold virus seemed to be the diversity rather than the sheer quantity of social contacts."

19.	Why do these results fall short of demonstrating that by broadening our social networks we can increase our resistance to respiratory infections? (Pick the best answer.)	
A)	Volunteers were used.	
B)	We're not told the age of the volunteers.	
C)	We're not told what day of the week they got the nasal spray.	
D)	Maybe the subjects lied about their relationships.	
E)	Some other variables, associated with the breadth of one's social network, may be the real causes of higher resistance to colds.	

20.	A magazine article on preventing cancer says, "Eating one serving of tofu a week may cut your risk of breast cancer 15%, recent research suggests." If the data comes from an observational study, then	
A)	the results must be false.	
B)	the results must be true.	
C)	there may be lurking variables.	
D)	perhaps those who chose to eat more tofu are, for some reason, less susceptible to breast cancer than those who didn't.	
E)	Both (C) and (D) are true.	

21.	The evidence that smoking causes lung cancer is very strong.  But it is not the strongest possible statistical evidence because	
A)	we can't do experiments to compare smokers and non-smokers.	
B)	only smokers have been studied.	
C)	the studies of the effects of smoking are not double-blind.	
D)	all the studies of the effects of smoking involve animals, not humans.	

22.	A high correlation between two variables does not always mean that changes in one causes changes in the other. The best way to get good evidence that cause-and-effect is present is to	
A)	make side-by-side boxplots.	
B)	carry out a randomized comparative experiment.	
C)	make a histogram and look for outliers.	
D)	make a scatterplot and look for a strong association.	
E)	select a simple random sample from the population of interest.	

23.	The best way to settle questions of causation is	
A)	a careful observational study.	
B)	a properly designed experiment.	
C)	draw a scatterplot.	
D)	draw a line graph.	
E)	calculate a correlation.	

24.	A study of many countries finds a strong positive correlation between the life expectancy in a country and the percentage of households in the country with telephones.  This means that	
A)	telephone use is a major contributing cause of longer life.	
B)	life expectancy could be significantly increased by installing more telephones.	
C)	in countries where life expectancy is high, telephone ownership tends to be low.	
D)	in countries where telephone ownership is low, life expectancy tends to be high.	
E)	None of the above.	

25.	Martin would like to show that drinking one beer before a STAT 001 exam improves students' exam scores. The most convincing way to show this is	
A)	ask all STAT 001 students whether or not they drank a beer before the exam, then compare the mean scores of those who did and those who did not.	
B)	ask all STAT 001 students if they think that drinking a beer helps them on exams.	
C)	interview 50 students who got an A on the exam and 50 students who got a D and compare their beer drinking.	
D)	randomly choose 50 students to drink beer before the exam and another 50 to abstain from beer. Compare the mean exam scores in the two groups.	

26.	There is a positive correlation between the size of a hospital (measured by number of beds) and the median number of days that patients remain in the hospital.  Does this mean that you can shorten a hospital stay by choosing to go to a small hospital?	
A)	No—a negative correlation would allow that conclusion, but this correlation is positive.	
B)	Yes—the data show that stays are shorter in smaller hospitals.	
C)	No—the positive correlation is probably explained by the fact that seriously ill people go to large hospitals.	
D)	Yes—the correlation can't just be an accident.	

27.	Deaths from highway accidents went down after the adoption of a national 55 mile-per-hour speed limit.  Can we be confident that the lower speed limit caused the drop in deaths?	
A)	Yes, because the study was a randomized, comparative experiment.	
B)	No, because the effect of lower speed limits is confounded with the effect of better highways and safer cars.	
C)	Yes, because a drop in deaths over several years can't happen just by chance.	
D)	No, because of the placebo effect.	
E)	Yes, because correlation implies causation.	

28.	A high correlation between two variables does not always mean that changes in one cause changes in the other.  The best way to get good evidence that cause-and-effect is present is to	
A)	select a simple random sample from the population of interest.	
B)	arrange the data in a two-way table.	
C)	carry out a randomized comparative experiment.	
D)	make a scatterplot and look for a strong association.	
E)	make a histogram and look for outliers.	

29.	Perfect correlation means all of the following except	
A)	r = –1 or r = +1.	
B)	all points on the scatterplot lie on a straight line.	
C)	all variation in one variable is explained by variation in the other variable.	
D)	there is a causal relationship between the variables.	
E)	each variable is a perfect predictor of the other.	

30.	A report in a medical journal notes that the risk of developing Alzheimer's disease among subjects who (voluntarily) regularly took the anti-inflammatory drug ibuprofen (the active ingredient in Advil) was about half the risk among those who did not. Is this good evidence that ibuprofen is effective in preventing Alzheimer's disease?	
A)	Yes, because the study was a randomized, comparative experiment.	
B)	No, because the effect of ibuprofen is confounded with the placebo effect.	
C)	Yes, because the results were published in a reputable professional journal.	
D)	No, because this is an observational study. A clinical trial would be needed to confirm (or not confirm) the observed effect.	
E)	Yes, because a 50% reduction can't happen just by chance.	

31.	A study of 3,617 adults found that those who attend religious services live longer (on the average) than those who don't.  Is this good evidence that attending services causes longer life?	
A)	Yes, because the study is an experiment.	
B)	No, because religious people may differ from non-religious people in other ways, such as smoking and drinking, that affect life span.	
C)	Yes, because the sample is so large that the margin of error will be quite small.	
D)	No, because we can't generalize from 3,617 people to the millions of adults in the country.	

32.	Consider a large number of countries around the world.  There is a positive correlation between the number of Nintendo games per person x and the average life expectancy y.  Does this mean that we could increase the life expectancy in Rwanda by shipping Nintendo games to that country?	
A)	Yes; the correlation says that as the number of Nintendo games per person goes up, so does life expectancy.	
B)	No; if the correlation were negative we could accept that conclusion, but this correlation is positive.	
C)	Yes; positive correlation means that if we increase x, then y will also increase.	
D)	No; the positive correlation just shows that richer countries have both more Nintendo games per person and higher life expectancies.	
E)	It makes no sense to calculate correlation between these variables.	

33.	You wonder whether drinking coffee before a statistics exam improves the performance of students on the exam.  The best way to get good evidence of the effect of coffee on exam scores is	
A)	find out which students drink coffee before the exam and which do not; compare their exam scores.	
B)	take an opinion poll, asking students if they think coffee helps them stay alert.	
C)	get your friends to drink coffee before Exam 1 but not before Exam 2; compare their scores on the two exams.	
D)	assign some students, chosen at random, to drink coffee and others to avoid coffee before the exam; compare their exam scores.	

34.	Dr. Stats plans to toss a fair coin 10,000 times in the hope that it will lead him to a deeper understanding of the laws of probability.  Which of the following statements is true?	
A)	It is unlikely that Dr. Stats will get more than 5,000 heads.	
B)	Whenever Dr. Stats gets a string of 15 tails in a row, it becomes more likely that the next toss will be a head.	
C)	The fraction of tosses resulting in heads should be close to 1/2.	
D)	The chance that the 100th toss will be a head depends somewhat on the results of the first 99 tosses.	
E)	All of the above statements are true.	

Use the following to answer questions 35-36:

A recent Gallup Poll asked, "Do you consider the amount of federal income tax you have to pay as too high, about right, or too low?" 52% of the sample answered "Too high."  Gallup says that: “For results based on the sample of national adults (n = 1,021) surveyed April 6-9, 2008, the margin of sampling error is ± 3 percentage points.”

35.	The poll was carried out by telephone, so people without phones are always excluded from the sample.  Any errors in the final result due to excluding people without phones	
A)	are included in the announced margin of error.	
B)	are in addition to the announced margin of error.	
C)	can be ignored, because these people are not part of the population.	
D)	can be ignored, because this is a nonsampling error.	

36.	If Gallup had used an SRS of size n =1021 and obtained the sample proportion p = 0.52 , you can calculate that the margin of error for 95% confidence would be	
A)	±0.025  percentage points.	
B)	±0.05  percentage points.	
C)	±1.6  percentage points.	
D)	±3,0  percentage points.	
E)	±3.1  percentage points.	

Use the following to answer questions 37-41:

The student newspaper at a college asks an SRS of 250 undergraduates, "Do you favor eliminating supplemental fees for lab courses?"   In all, 150 of the 250 are in favor.

37.	The ___________ you want to estimate is the proportion p of all undergraduates who favor eliminating the carnival.	
A)	bias	
B)	confidence level	
C)	mean	
D)	parameter	
E)	statistic	

38.	To estimate p, you will use the proportion p = 150/250 of your sample who favored eliminating supplemental fees for lab courses.  The number p is a	
A)	bias.	
B)	confidence level.	
C)	mean.	
D)	parameter.	
E)	statistic.	

39.	A 95% confidence interval for the population proportion p is	
A)	150 ± 0.03.	
B)	0.6 ± 0.03.	
C)	150 ± 0.06.	
D)	0.6 ± 0.06.	
E)	1.67 ± 0.03.	

40.	A 90% confidence interval based on this same sample would have	
A)	the same center and a larger margin of error.	
B)	the same center and a smaller margin of error.	
C)	a larger margin of error and probably a different center.	
D)	a smaller margin of error and probably a different center.	
E)	the same center, but the margin of error changes randomly.	

41.	Suppose that (unknown to you) 55% of all undergraduates favor eliminating supplemental fees for lab courses.  If you took a very large number of simple random samples of size n = 250 from this population, the sampling distribution of the sample proportion p would be normal with	
A)	mean 0.55 and standard deviation 0.015.	
B)	mean 0.60 and standard deviation 0.06.	
C)	mean 0.55 and standard deviation 0.06.	
D)	mean 0.60 and standard deviation 0.03.	
E)	mean 0.55 and standard deviation 0.03.	

42.	You want to estimate the proportion of undergraduates at a college who favor eliminating evening exams.  You will choose an SRS.  If you enlarge your SRS from 250 to 1000 students, the sample proportion p	
A)	will have the same mean and the same standard deviation.	
B)	will have smaller bias and the standard deviation will be 1/4 as large.	
C)	will have smaller bias and the standard deviation will be 1/2 as large.	
D)	will have the same mean and the standard deviation will be 1/4 as large.	
E)	will have the same mean and the standard deviation will be 1/2 as large.	

43.	The phrase "95% confidence" in a Gallup Poll press release means that	
A)	our results are true for 95% of the population of all adults.	
B)	95% of the population falls within the margin of error we announce.	
C)	the probability is 0.95 that a randomly chosen adult falls in the margin of error we announce.	
D)	we got these results using a method that gives correct answers in 95% of all samples.	

Use the following to answer questions 44-46:

A recent Gallup Poll interviewed a random sample of 1,523 adults. Of these, 868 bought a lottery ticket in the past year.

44.	A 95% confidence interval for the proportion of all adults who bought a lottery ticket in the past year is (assume Gallup used an SRS)	
A)	0.57 ± 0.00016.	
B)	0.57 ± 0.00032.	
C)	0.57 ± 0.013.	
D)	0.57 ± 0.025.	
E)	0.57 ± 0.03.	

45.	Suppose that in fact (unknown to Gallup) exactly 60% of all adults bought a lottery ticket in the past year.  If Gallup took many SRSs of 1,523 people, the sample proportion who bought a ticket would vary from sample to sample.  The sampling distribution would be close to normal with	
A)	mean 0.6 and standard deviation 0.00016.	
B)	mean 0.6 and standard deviation 0.0126.	
C)	mean 0.6 and standard deviation 0.4899.	
D)	mean 0.6 and standard deviation 0.0251.	

46.	The same Gallup Poll asked its 1,523 adult respondents and also 501 teens (ages 13 to 17) whether they generally approved of legal gambling: 63% of adults and 52% of teens said yes.  The margin of error for a 95% confidence statement about teens would be	
A)	greater than for adults, because the teen sample is smaller.	
B)	less than for adults, because the teen sample is smaller.	
C)	less than for adults, because there are fewer teens in the population.	
D)	the same as for adults, because they both come from the same sample survey.	
E)	Can't say, because it depends on what percent of each population was in the sample.	

Use the following to answer question 47:

A surprising fact: 66% of all teenagers have a TV set in their room.  If an opinion poll chooses an SRS of 1,000 teens and asks if they have a TV set in their room, the percent who say "Yes" will vary if the sample is repeated.  In fact, the percent "Yes" in many samples will follow a normal distribution with mean 66% and standard deviation 1.5%.

47.	The variation from sample to sample when the poll is repeated is described by the standard deviation (1.5%).  We would like this variation to be small, so that repeated polls give almost the same result.  To reduce the standard deviation, we could	
A)	use an SRS of size less than 1,000.	
B)	use an SRS of size greater than 1,000.	
C)	use a confidence level less than 95%.	
D)	use a confidence level greater than 95%.	
E)	Both (B) and (C).	

48.	The margin of error for a 95% confidence interval is 2.8. If we decrease the confidence level to 90%, the margin of error will be	
A)	biased.	
B)	99%.	
C)	2.8.	
D)	smaller than 2.8.	
E)	larger than 2.8.	

49.	For a 95% confidence interval, a larger sample size will generally give	
A)	a least-squares line.	
B)	a larger margin of error.	
C)	less bias.	
D)	higher correlation.	
E)	a smaller margin of error.	

50.	If we take a simple random sample of size n = 500 from a population of size 500,000, the variability of our estimate will be	
A)	less than the bias.	
B)	approximately the same as the variability for a sample of size n = 500 from a population of size 50,000,000.	
C)	plus or minus 0.1%.	
D)	much greater than the variability for a sample of size n = 500 from a population of size 50,000,000.	
E)	much less than the variability for a sample of size n = 500 from a population of size 50,000,000.	

51.	A sample survey finds that 30% of a sample of 874 Ohio adults said good health was the thing they were most thankful for. If that sample were an SRS from the population of all Ohio adults, what would be the 99% confidence interval for the percent of all Ohio adults who feel that way?	
A)	25% to 35%	
B)	26% to 34%	
C)	27% to 33%	
D)	28% to 32%	
E)	29% to 31%	

52.	If the 874 people in the previous question had called a 900 number to give their opinions, how would this affect your response?	
A)	Not at all, because the width of the confidence interval depends only on the sample size, and not on the population size.	
B)	Not at all, because the width of the confidence interval depends only on the sample size, and not on how the sample was obtained.	
C)	It would be wider because voluntary response polls have a bigger margin of error than SRSs.	
D)	It would be narrower because voluntary response polls are less variable than SRSs.	
E)	A confidence interval makes no sense for a voluntary response sample.	

53.	A poll of 1,234 adults found that 62% expect an increase in environmental pollution in the next decade.  Take the poll's sample to be an SRS of all adults.  Which of these is a correct 95% confidence statement?	
A)	With 95% confidence, the percent of the sample who expect pollution to increase is between 60.6% and 63.4%.	
B)	With 95% confidence, the percent of the sample who expect pollution to increase is between 59.2% and 64.8%.	
C)	With 95% confidence, the percent of all adults who expect pollution to increase is between 60.6% and 63.4%.	
D)	With 95% confidence, the percent of all adults who expect pollution to increase is between 59.2% and 64.8%.	
E)	With 95% confidence, the percent of all adults who expect pollution to increase is between 59% and 65%.	

54.	A CBS News/New York Times opinion poll asked 1,190 adults whether they would prefer balancing the federal budget over cutting taxes; 702 of those asked said "Yes."  Take the sample to be an SRS from the population of all adults.  Which of these is a correct 95% confidence interval for the proportion of all adults who prefer balancing the budget to cutting taxes?	
A)	0.59 ± 0.0004	
B)	0.59 ± 0.014	
C)	0.59 ± 0.0186	
D)	0.59 ± 0.0285	
E)	0.59 ± 0.037	

55.	You choose an SRS of 2,000 women over 18 years of age from the New York City metropolitan area; 623 of them are single.  A 95% confidence interval for the proportion of all adult women in the New York area who are single is (approximately)	
A)	0.31 ± 0.03.	
B)	0.62 ± 0.03.	
C)	0.31 ± 0.02.	
D)	0.62 ± 0.02.	
E)	0.20 ± 0.03.	

56.	An ad for ARCO graphite motor oil says (really): "Based on a 95% confidence level, our tests achieved between 1% and 8.7% mileage improvement" as compared with a conventional motor oil. What does the phrase "95% confidence level" mean here?	
A)	ARCO graphite beats 95% of conventional motor oils.	
B)	The interval from 1% to 8.7% covers 95% of the mileage improvements observed in the tests.	
C)	The tests included 95% of all oil brands on the market.	
D)	The estimate that mileage improves somewhere between 1% and 8.7% came from a method that would catch the true improvement in 95% of all similar tests.	
E)	A mistake has been made, because 95% + 8.7% is more than 100%.	

Use the following to answer questions 57-60:

A poll of 1,190 adults found that 702 said they would prefer balancing the budget over cutting taxes.

57.	The sample proportion who prefer balancing the budget is	
A)	unknown, because we only have information on 1,190 people.	
B)	unknown until we decide what confidence level we want.	
C)	1.70.	
D)	0.59.	
E)	0.41.	

58.	Suppose that the poll used an SRS.  A 95% confidence interval for the proportion of all adults who prefer balancing the budget to cutting taxes is	
A)	0.41 ± 0.0285.	
B)	0.59 ± 0.0285.	
C)	0.41 ± 0.0004.	
D)	0.59 ± 0.0004.	
E)	0.59 ± 0.0143.	

59.	A member of Congress thinks that 95% confidence isn't enough. He wants to be 99% confident.  How would the margin of error of a 99% confidence interval based on the same sample compare with the 95% interval you found in the previous question?	
A)	It would be smaller, because it omits only 1% of the possible samples instead of 5%.	
B)	It would be the same, because the sample is the same.	
C)	It would be larger, because higher confidence requires a larger margin of error.	
D)	Can't tell, because the margin of error is random.	
E)	Can't tell, because it depends on the size of the population.	

60.	Another member of Congress is satisfied with 95% confidence, but she wants a smaller margin of error. How can we get a smaller margin of error, still with 95% confidence?	
A)	Take a larger sample, because larger samples result in smaller margins of error.	
B)	Take a smaller sample, because smaller samples result in smaller margins of error.	
C)	Take another sample of the same size and you might be lucky and get a much smaller margin of error.	
D)	Take a sample of adults in Indiana instead of in the entire country.  Then the population will be smaller and this will give a smaller margin of error.	
E)	Carry out a call-in poll to get a voluntary response sample. Voluntary response samples have no margin of error.	

Use the following to answer questions 61-63:

The New York Times conducted a poll on women's issues in June of 1989.

61.	One question asked was, "Many women have better jobs and more opportunities than they did 20 years ago.  Do you think women have had to give up too much in the process, or not?"  Of the 1,025 women who were asked, 492 said "Yes."  Take these 1,025 women to be an SRS of all adult women.  Which of these is a correct 95% confidence interval for the proportion of all adult women who would say "Yes" to this statement?	
A)	0.48 ± 0.031	
B)	0.48 ± 0.000487	
C)	0.48 ± 0.0156	
D)	0.492 ± 0.031	
E)	0.492 ± 0.0156	

62.	In the previous question, you obtained a 95% confidence interval for this telephone sample.  The bias due to leaving out people without a telephone	
A)	is included in the margin of error.	
B)	is not included in the margin of error, because leaving out people with no phone is a nonsampling error.	
C)	is not included in the margin of error, because leaving out people with no phone has no effect on the outcome of the poll.	
D)	is not included in the margin of error, because the margin of error only covers the chance variation in a random sample.	

63.	The 472 men were also asked the question, "Many women have better jobs and more opportunities than they did 20 years ago.  Do you think women have had to give up too much in the process, or not?"  above, and 212 of them said "Yes."  The margin of error for a 95% confidence interval for men would be	
A)	larger than for women, because fewer men were asked.	
B)	smaller than for women, because fewer men were asked.	
C)	larger than for women, because fewer men said "Yes."	
D)	smaller than for women, because fewer men said "Yes."	
E)	the same as for women.	

64.	A recent survey of 35,101 randomly selected U.S. adults studied the religious affiliation of Americans.  The survey interviewed 245 people in Maine.  Suppose that this is a simple random sample of adult residents of Maine.  Of these 245 people, 56 said they attend religious services at least once a week.  A 95% confidence interval for the proportion of all residents of Maine who attend religious services at least once a week is closest to	
A)	0.202 to 0.256.	
B)	0.175 to 0.282.	
C)	0.215 to 0.242.	
D)	0.228 to 0.230.	

65.	If an SRS of size n = 1500 has sample proportion p = 0.55 approving of the president, a 95% confidence interval for the proportion p of all adults who approve is	
A)	0.55 ± 0.00033.	
B)	0.55 ± 0.013.	
C)	0.55 ± 0.026.	
D)	0.55 ± 0.03.	

66.	Most people can roll their tongues, but many people can't. Whether or not a person can roll his tongue is genetically determined. Suppose we are interested in determining what fraction of students can roll their tongues. We get a simple random sample of 400 students and find that 317 can roll their tongues. The margin of error for a 95% confidence interval for the true percentage of tongue-rollers among students is closest to	
A)	0.8%.	
B)	2.0%.	
C)	3.0%.	
D)	4.0%.	
E)	20.75%.	

67.	A recent survey of 35,101 randomly selected U.S. adults studied the religious affiliation of Americans.  The sample for this survey is	
A)	religious affiliation.	
B)	the 35,101 people questioned.	
C)	all adults with telephones.	
D)	all U.S. adults.