Download Quiz 4 - Brandywine School District

Final Exam Review Chapters 1-5
Name:
Multiple choice. Circle the letter corresponding to the best answer choice.
1. One of the following 12 scores
84 76 92 92 88 96 68 80 92 88 76 96
was omitted from the stemplot at the right:
The missing number is
(a) 76
(b) 88
(c) 92
(d) 96
(e) 92266
2. If a bar graph is to be accurate, it is essential that
(a) the bars touch each other.
(b) the bars be drawn vertically.
(c) both horizontal and vertical scales be clearly marked in equal units.
(d) the bars all have the same width.
(e) the explanatory variable be plotted on the horizontal axis.
3. You want to make a graph that shows how the cost of attending the University of Michigan has
increased since 1980. A good choice of graph would be a
(a) boxplot.
(b) histogram.
(c) line graph.
(d) pie chart.
(e) bar graph.
4. The five-number summary of the distribution of scores on the final exam in Psych 001 last semester
was 18 39 62 76 100. A total of 416 students took the exam. About how many students had
scores above 39?
(a) 416
(b) 312
(c) 104
(d) 400
(e) 250
5. The "average" income of American households in 1998 was either $38,885 or $51,855, depending
on whether we use the mean or median to measure center. We can say that
(a) $38,885 is the mean because income distributions are skewed to the left.
(b) $51,855 is the mean because income distributions are skewed to the left.
(c) $38,885 is the mean because income distributions are skewed to the right.
(d) $51,855 is the mean because income distributions are skewed to the right.
(e) One of the numbers must be wrong because income distributions are close to symmetric.
6. You have data on the summer earnings of a sample of 1,000 high school students. What kind of
graph should you use to describe the distribution of their earnings?
(a) Bar graph.
(b) Histogram.
(c) Line graph.
(d) Pie chart.
(e) None of these.
Here is a stemplot of the percent of adult males who are illiterate in 142 countries, according to the
United Nations. For example, the highest illiteracy rate was 79%, in the African country Niger.
7. The overall shape of this distribution is
(a) clearly skewed to the right
(b) clearly skewed to the left
(c) roughly symmetric
(d) no clear shape
8. To locate the median of 142
observations, you would count up to what
position after arranging the data in order
from smallest to largest?
(a) half-way between the 12th and 13th in
the ordered list.
(b) 50th in the ordered list.
(c) 71st in the ordered list.
(d) 72nd in the ordered list.
(e) half-way between the 71st and 72nd in
the ordered list.
9. The mean of this distribution (don't try to find it) is certainly
(a) very close to the median.
(b) clearly less than the median.
(c) clearly greater than the median.
(d) can't say because the mean is random.
10. Based on the shape of this distribution, what numerical measures would best describe it?
(a) the five-number summary.
(b) the mean and standard deviation.
(c) the mean and the quartiles.
(d) the median and the standard deviation.
(e) none of these
Suppose that the BAC of male students at a particular college who drink 5 beers varies from student to
student according to a normal distribution with mean 0.08 and standard deviation 0.01. The next three
questions use this information.
11. The middle 95% of students who drink 5 beers have BAC between
(a) 0.07 and 0.09
(b) 0.06 and 0.10
(c) 0.05 and 0.11
(d) 0.04 and 0.12
12. What percent of students who drink 5 beers have BAC above 0.08 (the legal limit for driving in
most states)?
(a) 2.5%
(b) 5%
(c) 16%
(d) 32%
(e) 50%
13. What percent of students who drink 5 beers have BAC above 0.10 (the legal limit for driving other
states)?
(a) 2.5%
(b) 5%
(c) 16%
(d) 32%
(e) 50%
14. SAT scores are normally distributed with mean 500 and standard deviation 100. Julie scores 650.
Her standard score is
(a) 150
(b) 15
(c) 1.5
(d) 0.15
15. Fifty percent of the observations in any distribution will be between
(a) the quartiles
(b) the mean plus or minus one standard deviation
(c) the mean plus or minus two standard deviations
(d) the mean plus or minus three standard deviations
(e) the mean and the standard deviation
16. For a normal distribution with mean 20 and standard deviation 5, approximately what percent of
the observations will be between 5 and 35?
(a) 50%
(b) 68%
(c) 95%
(d) 99.7%
(e) 100%
17. For a normal distribution with mean 20 and standard deviation 5, approximately what percent of
the observations will be less than 20?
(a) 50%
(b) 68%
(c) 95%
(d) 99.7%
(e) 100%
18. For a normal distribution with mean 20 and standard deviation 5, approximately what percent of
the observations will be less than 10?
(a) 99.7%
(b) 97.5%
(c) 2.5%
(d) 95%
(e) 99%
19. A normal distribution always
(a) is skewed to the right
(b) is skewed to the left
(c) is symmetric
(d) has a mean of 0
(e) has more than one peak
20. The United Nations also has data on the percent of adult females who are illiterate in each of these
142 countries. The correlation between male illiteracy rate and female illiteracy rate is
r = 0.945. This tells us that
(a) countries with high male illiteracy tend to also have high female illiteracy, and the relationship is
very strong.
(b) countries with high male illiteracy tend to also have high female illiteracy, but the two are only
weakly related.
(c) countries with high male illiteracy tend to have low female illiteracy, and the relationship is very
strong.
(d) countries with high male illiteracy tend to have low female illiteracy, but the two are only weakly
related.
(e) there is very little relationship between the illiteracy rates for males and females.
21. The least-squares regression line for predicting the percent of a country's females who are illiterate
from the percent of males who are illiterate is
female % = 3.34 + 1.39  male %
In China, 10.1% of men are illiterate. Predict the percent of illiterate women in China.
(a) 4.7%
(b) 14%
(c) 17.4%
(d) 47.8%
22. The equation of the regression line tells us that (on the average) when the male illiteracy rate goes
up by 1%, the female rate goes up by
(a) 4.73%
(b) 3.34%
(c) 1.95%
(d) 1.39%
23. You are planning an experiment to study the effect of gasoline brand and vehicle weight on the gas
mileage (miles per gallon) of sport utility vehicles. In this study,
(a) gas mileage is a response variable.
(b) gas mileage is an explanatory variable.
(c) gas mileage is a lurking variable.
(d) gas mileage is a categorical variable.
24. 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.
25. A correlation cannot have the value
(a) 0.4
(b) -0.75
(c) 1.5
(d) 0.0
(e) 0.99
26. Which correlation indicates a strong positive straight line relationship?
(a) 0.4
(b) -0.75
(c) 1.5
(d) 0.0
(e) 0.99
27. A study of child development measures the age (in months) at which a child begins to talk and also
the child's score on an ability test given several years later. The study asks whether the age at which a
child talks helps predict the later test score. The least-squares regression line of test score y on age x is
y = 110 1.3x. According to this regression line, what happens (on the average) when a child starts
talking one month later?
(a) The test score goes down 110 points.
(b) The test score goes down 1.3 points.
(c) The test score goes up 110 points.
(d) The test score goes up 1.3 points.
(e) The test score is 108.7.
28. A study of home heating costs collects data on the size of houses and the monthly cost to heat the
houses with natural gas. Here are the data.
Just by looking at the data (don't do a calculation) you can see that the correlation between
house size and heating cost is
(a) close to zero.
(b) clearly positive.
(c) clearly negative.
(d) not close to zero, but could be either positive or negative.
(e) makes no sense for these data.
29. A friend tells you that the correlation for the data in the previous question is r = 0.99984.
You conclude from this number that
(a) larger houses cost more to heat than smaller houses, and the relationship is almost perfectly
straight.
(b) smaller houses cost more to heat than larger houses, and the relationship is almost perfectly
straight.
(c) larger houses cost more to heat than smaller houses, but the relationship is not very strong.
(d) smaller houses cost more to heat than larger houses, but the relationship is not very strong.
(e) your friend made a mistake, because the value of r is impossible.
30. 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.
31. 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.
32. An engineer at General Motors collects data on the weights (in pounds) and the fuel economy (in
miles per gallon) of all model year 2000 cars sold by GM. We expect the correlation between weight
and gas mileage to be
(a) clearly positive
(b) close to zero
(c) clearly negative
(d) can't tell because correlation is random
(e) can't tell because correlation depends on the average fuel economy of these cars.
33. A plausible value for the correlation between heights of two children of the same parents is
(a) -0.95
(b) -0.50
(c) close to 0
(d) +0.50
(e) +0.95
34. Which of the following statements about correlation r is false?
(a) The correlation r describes how tightly the points on a scatterplot cluster about a straight line.
(b) The correlation r can never take a value larger than 1.
(c) The value of r is heavily influenced by outliers.
(d) The correlation r cannot be 0.
35. Which of these statements is true of the correlation r?
(a) r always takes values 0 or greater than 0.
(b) r always takes values between -1 and 1.
(c) r describes only straight line relationships.
(d) Both (a) and (c).
(e) Both (b) and (c).
______________________________________________________________
1. A table of random numbers is used to select 30 students from a statistics class to rate a statistics
video. These 30 students are
(a) the sampling frame
(b) the population
(c) a simple random sample of the class
(d) a census
(e) a voluntary response sample
2. A table of random numbers is used to select 30 students from a statistics class to rate a statistics
video. The ratings that these students give are used to estimate the ratings that would be given if the
entire class were asked to rate the video. The average of the ratings of all students in the class is
(a) a population parameter
(b) a convenience sample
(c) a census
(d) the population
(e) a statistic that is an unbiased estimate of the class rating
3. In a table of 500 random digits
(a) the number one will appear exactly 50 times
(b) the number one will appear approximately 10 times
(c) the numbers from 1 to 10 are equally likely
(d) the chance that the first number is one is the same as the chance that the first number is two
(e) the average of these numbers will be 5
4. Which of the following is correct?
(a) parameters describe population characteristics
(b) parameters describe sample characteristics
(c) the population is a subset of the sample
(d) statistics must be based on a simple random sample
5. A survey was sent to a simple random sample of college sophomores. The sample size was 300.
When asked whether or not they liked Willie Nelson's music, 35 of these students did not give any
answer. This is an example of
(a) a stratified sample
(b) a census
(c) bias
(d) nonresponse
(e) the margin of error
6. When Ann Landers asked her readers to tell her "if your sex life has gone downhill after marriage,"
more than 100,000 people responded. This is an example of
(a) a simple random sample.
(b) a well designed survey.
(c) a stratified sample.
(d) a convenience sample.
(e) a voluntary response sample.
A national sample survey interviewed 3,800 people age 18 and older nationwide by telephone. One
question asked was whether they agreed with this statement: "Some people say we should have a third
major political party in this country in addition to the Democrats and Republicans." The next five
questions concern this opinion poll
7. The population for this sample survey appears to be
(a) all U.S. citizens.
(b) all adult residents of the U.S.
(c) all registered voters.
(d) the 3,800 people who were interviewed.
(e) people who think we should have a third political party.
8. 53% of the people asked agreed that we should have a third party. The number 53% is a
(a) margin of error. (b) statistic. (c) confidence level. (d) correlation.
(e) parameter.
9. The news article that reports the poll results says, "The margin of error is plus or minus two
percentage points." This means that
(a) we can be 95% confident that 53% of all Americans think we should have a third party.
(b) we can be 95% confident that between 51% and 55% of all Americans think we should have a third
party.
(c) we can be 95% confident that between 51% and 55% of the 3,800 people interviewed think we
should have a third party.
(d) we can be between 93% and 97% confident that 53% of all Americans think we should have a third
party.
(e) we can be sure that between 51% and 55% of all Americans think we should have a third party.
10. Among the poll respondents who were between 18 and 24 years old, 60% agreed that we should
have a third political party. The margin of error that goes with this result is
(a) less than  2%, because only some of the population is between 18 and 24, so it's easier to
estimate facts about them.
(b) less than  2%, because there are fewer than 3,800 people 18 to 24 in the sample.
(c) greater than  2%, because there are fewer than 3,800 people 18 to 24 in the sample.
(d) greater than  2%, because only some of the population is between 18 and 24, so it's harder to
estimate facts about them.
(e) equal to  2%, because this result comes from the same sample survey.
11. The most common national opinion polls have a margin of error of  3%. This survey has a
smaller margin of error (  2%) because
(a) the size of the sample is larger than the usual sample size, which is about 1,500 people.
(b) the size of the sample is smaller than the usual sample size, which is about 5,000 people.
(c) the confidence level is less than that of most polls.
(d) fewer people refused to answer questions in this poll than in most polls.
(e) the confidence level is greater than that of most polls.
12. You want to take an SRS of 50 of the 816 students who live in a college dormitory. You label the
students 001 to 816 in alphabetical order. In the table of random digits you read the entries
96746 12149 37823 71868 18442 35119 62103 39244
The first three students in your sample have labels
(a) 967, 121, 378
(b) 461, 214, 718
(c) 674, 612, 149
(d) 967, 461, 214
(e) 461, 214, 937
13. Another correct choice of labels for the 816 students in the previous question is
(a) 000 to 816 in alphabetical order.
(b) 001 to 816 in order of the student ID numbers.
(c) 000 to 815 in alphabetical order.
(d) Both (b) and (c) are correct.
(e) All of (a), (b), and (c) are correct.
14. Which of these statements about the table of random digits is true?
(a) Every row must have exactly the same number of 0's and 1's.
(b) In the entire table, there are exactly the same number of 0's and 1's.
(c) If you look at 100 consecutive pairs of digits anywhere in the table, exactly 1 pair is 00.
(d) All of these are true.
(e) None of these is true.
15. The Gallup poll interviews 1600 people. Of these, 18% say that they jog regularly. The news report
adds that "The poll had a margin of error of plus or minus three percentage points." You can safely
conclude that
(a) if Gallup took many samples, 95% of them would find that exactly 18% of the people in the sample
jog.
(b) 95% of all Gallup poll samples like this one give answers within  3% of the true population value.
(c) the percent of the population who jog is certain to be between 15% and 21%.
(d) 95% of the population jog between 15% and 21% of the time.
(e) we can be 3% confident that the sample result is true.
16. How many of the 1600 people in the Gallup Poll sample in the previous problem said that they jog
regularly?
(a) 89
(b) 288
(c) 1312
(d) Between 240 and 336, because of the margin of error.
(e) We can't say exactly, because we are only 95% confident.
Sale of eggs that are contaminated with salmonella can cause food poisoning among consumers. A
large egg producer takes an SRS of 200 eggs from all the eggs shipped in one day. The laboratory
reports that 9 of these eggs had salmonella contamination. Unknown to the producer, 0.1% (one-tenth
of one percent) of all eggs shipped had salmonella.
The next four questions refer to this situation.
17. In this situation,
(a) both 0.1% and 9 are parameters.
(b) both 0.1% and 9 are statistics.
(c) 0.1% is an estimate and 9 is a margin of error.
(d) 0.1% is a parameter and 9 is a statistic.
(e) 9 is a parameter and 0.1% is a statistic.
18. Based on the sample data, the producer estimates that the proportion of contaminated eggs in the
population is about
(a) 0.045%.
(b) 0.2%. (c) 20%.
(d) 4.5%.
(e) 3%.
19. A statistician tells the producer that the margin of error for a 95% confidence statement for these
data is about plus or minus 3 percentage points. The producer therefore reports that between 1.5% and
7.5% (that's 4.5%  3%) of all eggs are contaminated. This isn't right -- only 0.1% are contaminated.
What went wrong?
(a) The 4.5% is wrong -- see my answer to the previous problem for the correct estimate.
(b) A 95% confidence statement is only right for 95% of all possible samples. This must be one of the
5% for which we get an incorrect conclusion.
(c) The 4.5% is correct, and it's impossible for the truth to lie outside the margin of error, so there must
be another mistake.
(d) Maybe the laboratory counted contaminated eggs incorrectly.
20. If the producer took an SRS of 400 eggs instead of 200, the new margin of error would be
(a) can't tell, because the size of the sample doesn't control the margin of error.
(b) the same as before, because the population of eggs is the same.
(c) smaller than before, because the sample is larger.
(d) larger than before, because the sample is larger.
(e) random in size, could be either larger or smaller than before.
21. You will take a simple random sample of 3 cases from a population of 11 cases of wine, which are
marked A, B, C, D, E, F, G, H, I, J, K. You assign numbers as labels to the cases in order to use the
random digit table. Which of the following is an incorrect assignment?
22. When an opinion poll says that "with 95% confidence" the margin of error for its results is plus or
minus 3 percentage points, this means that
(a) between 92% and 98% of the people chosen for the sample were contacted.
(b) the percent of people who said "Yes" to the question was between 92% and 98%.
(c) we can be certain that the true population value is within  3 points of 95%.
(d) 95% of all samples chosen as this one was give results within  3 points of the true population
value.
(e) 95% of the people chosen for the sample were contacted.
23. An opinion poll asks a sample of 1100 people whether they support reducing the number
of legal immigrants to the U.S.; 53% of these 1100 people say "Yes." The number 53% is a
(a) statistic. (b) parameter. (c) margin of error. (d) reliability. (e) bias.
A Gallup Poll recently showed that 60 percent of Americans believe there is a hell. (The question was,
"Do you believe there is a place where those who led bad lives and died without repentance are
eternally damned?") The poll contacted 1,108 adults by telephone. The margin of sampling error was
plus or minus four percentage points. The next three questions refer to this Gallup Poll.
24. The population for this sample survey is
(a) the 1,108 people who answered the question.
(b) the 60% who answered "Yes" to the question.
(c) all adult residents of the United States.
(d) all households in the United States.
25. From the information given above, you can make the following statement. (Note that 60  4 is 56
percent to 64 percent.)
(a) Between 56 percent and 64 percent of all American adults believe there is a hell.
(b) Between 56 percent and 64 percent of the sample believe there is a hell.
(c) We are 95% confident (but not certain) that between 56% and 64% of all American adults believe
there is a hell.
(d) We are 95% confident (but not certain) that between 56% and 64% of the sample believe there is a
hell.
26. The poll has some bias because the sample leaves out people without a telephone. This bias
(a) is not included in the margin of error, because leaving out people with no phone is a nonsampling
error.
(b) is not included in the margin of error, because the margin of error only covers the chance variation
in a random sample.
(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 included in the  4% margin of error.
27. Voluntary response polls almost always suffer from
(a) the placebo effect.
(b) randomization.
(c) high bias.
(d) highly variable results.
28. If we took a SRS of 1700 people from California (population 32 million) and a SRS of 1000 people
from Detroit (population 1 million) which sample would have the smaller margin of error?
(a) Both would be the same, because simple random samples (SRS) are taken in both places.
(b) Detroit, because 1000/1,000,000 is more than 1700/32,000,000.
(c) Detroit, because it has the smaller population.
(d) California, because the sample size (1700) is larger than for Detroit (1000).
(e) California, because it has the larger population.
29. Compared with other types of probability sampling, a simple random sample (SRS) is
(a) the only method in which all individuals in the population are equally likely to be selected.
(b) the only method in which all possible samples have the same chance of being selected.
(c) the least expensive method for a national sample survey.
(d) all of the above.
30. If the sample size is much smaller than the population size, the margin of error of a simple random
sample depends on
(a) population size.
(b) sample size.
(c) Both of the above.
(d) Neither of the above.