CHAPTER 13
The Wechsler Adult Intelligence Scale (WAIS) is an IQ test. The scores on the
WAIS for the 20 to 34 years age group are approximately normally distributed
with a mean of 110 and a standard deviation of 15. The scores for the 60 to 64
years age group are approximately normally distributed with a mean of 90 and
Question a standard deviation of 15. Sarah, who is 30, scores 130 on the WAIS. Her
mother, who is 60, takes the test and scores 115.
True or false: Sarah’s mother scored higher than Sarah relative to her age
group.
True
False
Answer
If you use a computer to generate "random numbers" between 0 and 1, you will
get observations from a uniform distribution. The following figure shows the
density curve for a uniform distribution.
Question
The curve takes the constant value 1 between 0 and 1 and the value zero
outside this range.
True or false: The total area under the curve is 1.
Answer
Question
True
False
The distribution of heights of young men is
approximately Normal with a mean of 70 inches and a
standard deviation of 2.5 inches. Use the 68–95–99.7
rule to answer the following question.
Fill in the blank:
____ percent of men are shorter than 65 inches. (Give
your answer to one decimal place.)
Evaluation
Method
Exact Match 2.5
Question
Answer
Case Sensitivity
The distribution of the heights of young men is
approximately normal with a mean of 70 inches and a
standard deviation of 2.5 inches.
Fill in the blank:
The standard score of a height of 72 inches (6 feet) is ___.
(Give your answer to one decimal place.)
Evaluation
Method
Exact Match 0.8
Exact Match .8
Answer
Case Sensitivity
The length of human pregnancies from conception to birth varies according to
a distribution that is approximately Normal with a mean of 266 days and
standard deviation 16 days. Use the 68–95–99.7 rule to answer the following
Question
question.
Almost all (99.7 percent) pregnancies fall between ____ to ____ days.
A.
250, 282
Answer B.
218, 314
C.
234, 298
The length of horse pregnancies from conception to birth
varies according to a roughly Normal distribution with a
mean of 336 days and standard deviation 3 days. Use the
68–95–99.7 rule to answer the following question.
Question
Fill in the blank:
About ______ percent of horse pregnancies are less than
333 days.
Evaluation
Method
Exact Match 16
Answer
Case Sensitivity
The distribution of the heights of young men is approximately normal with a
mean of 70 inches and a standard deviation of 2.5 inches.
Question
The heights of the middle 95 percent of men fall between ___ inches and ___
inches.
A.
65, 75
Answer B.
62.5, 77.5
C.
67.5, 72.5
Question
Answer
The length of horse pregnancies from conception to birth varies according to a
roughly Normal distribution with a mean of 336 days and standard deviation 3
days. Use the 68–95–99.7 rule to answer the following question.
The correct range that contains the middle 95 percent of all horse pregnancies
is _____ to ______.
A.
333, 339
B.
330, 342
C.
327, 345
The length of human pregnancies from conception to birth varies according to
a distribution that is approximately Normal with a mean of 266 days and
standard deviation 16 days. Use the 68–95–99.7 rule to answer the following
Question
question.
How long are the longest 2.5 percent of all pregnancies?
A.
Longer than 282 days
Answer B.
Longer than 298 days
C.
Less than 234 days
Consider the Normal distribution with a mean of 111 and a
standard deviation of 11 as a description of the IQ test
scores of all rural Midwest seventh-grade students.
Question
Fill in the blank:
The percentage of IQ scores for rural Midwest seventhgraders that are less than 100 is ______.
Evaluation
Method
Answer
Case Sensitivity
Exact Match 16
Exact Match 16%
Congressman Floyd commissions a sample survey of voters to learn what
percentage favor him in his race for reelection. To avoid spending too much, he
samples only 50 voters. Suppose that only 43 percent of the voters support
Question Floyd. The percentage favoring Floyd in a random sample of size 50 will vary
from sample to sample according to a Normal distribution with a mean of 43
percent and a standard deviation of 7 percent. What percentage of all such
samples will (wrongly) show that half or more of the voters favor Floyd?
A.
0.15%
B.
Answer 2.5%
C.
16%
CHAPTER 17 HOMEWORK
You read in a book on poker that the probability of being dealt two pairs in a
Question five-card poker hand is 1/21.
Identify the correct interpretation of the given information:
A.
In the long run, of a large number of hands of five cards, about 4.8 percent
will contain two pairs.
Answer
B.
In the short run, of a series of hands of five cards, about 4.8 percent will
contain two pairs.
C.
In the long run, of a large number of hands of five cards, there is a probability
of 4.8 that a hand will contain two pairs.
Referring to the law of averages, C. S. Lewis once wrote: “If you tossed a coin
Question a billion times, you could predict a nearly equal number of heads and tails.”
Identify the statement that correctly states the law of averages.
A.
If you tossed a coin a billion times, you could predict nearly equal proportions
of heads and tails.
Answer
B.
If you tossed a coin a billion times, you could predict a nearly equal number
of heads and tails.
C.
If you tossed a coin a billion times, you could predict the number of heads to
be half of the total number of tosses.
The Pick 4 games in many state lotteries announce a four-digit winning
number each day. The winning number is essentially a four-digit group from a
table of random digits. You win if your choice matches the winning digits, in
exact order. The winning amount is divided among all players who matched
Question
the winning digits.
You consider two sequences: 2873 and 9999. Which sequence is more likely
to be the winning sequence?
A.
The sequence 9999 has a higher probability than the sequence 2873.
Answer B.
The sequence 2873 has a higher probability than the sequence 9999.
C.
Both sequences have equal probability.
A number of individuals were asked to estimate their probability of being in
an accident next year. Almost everyone says that their personal probability is
Question
lower than the random driver probability. Identify the most plausible
explanation.
A.
The random driver probability is based on random drivers, whereas the
personal probability is based on selected individuals.
B.
Answer
Most individuals drive safer than a randomly selected driver.
C.
Most individuals believe that they are better than average drivers.
Question
A particular baseball player gets a hit about 1/3 of the time over an entire
season. After he has failed to hit safely in nine straight at-bats, the TV
commentator says, “He is due for a hit by the law of averages.”
True or false: The commentator is correct because the player’s hitting average
of 1/3 is not attained in nine straight at-bats.
Answer
True
False
A number of individuals were asked to estimate their probability of being in
an accident next year. Why might personal probability possibly be a more
Question
accurate prediction of an individual's "true chance" of having an accident than
the probability for a random driver? Identify the most plausible explanation.
A.
Personal probability is based on accurate calculations.
B.
Answer
Personal probability is not biased.
C.
Personal probability might take into consideration specific information about
the individual.
A gambler knows that red and black are equally likely to occur on each spin of
a roulette wheel. He observes five consecutive reds occur and bets heavily on
black at the next spin. Asked why, he explains that black is “due by the law of
Question averages”.
Which of the following statements is correct about the gambler’s reasoning for
betting on black?
A.
The gambler’s reasoning is inappropriate because after five consecutive reds,
the probability of red in the next spin is higher than the probability of black.
B.
Answer
The gambler’s reasoning is inappropriate because even after five consecutive
reds, the probabilities of black and red in subsequent spins are equal.
C.
The gambler’s reasoning is appropriate because after five consecutive reds,
the probability of black in subsequent spins is higher than the probavility of
red.
Question
Identify the situation in which you would rely on a probability found as a
long-term proportion from data on many trials.
A.
Selling your old car
B.
Answer Taking your friend, who had an accident, to a doctor for first aid
C.
Choosing which brand of an expensive car to buy
CHAPTER 18 HOMEWORK
There are 36 possible outcomes when you roll two casino dice and record upfaces in order (first die, second die). What is the probability that the sum of
Question the spots on up-faces is 7 or 11?
(Hint: Examine Figure 18.1 on pg. 426 of the book.)
A.
0.165
B.
0.122
Answer C.
0.034
D.
0.222
A roulette wheel has 38 slots, numbered 0, 00, and 1 to 36. The slots 0 and 00
are colored green, 18 of the others are red, and 18 are black. The dealer spins
Question
the wheel and at the same time rolls a small ball along the wheel in the
opposite direction. The wheel is carefully balanced, so that the ball is equally
likely to land in any slot when the wheel slows down. Gamblers can bet on
various combinations of numbers and colors.
If you bet on red, you win if the ball lands in a "red" slot. What is the
probability of winning?
A.
18/38
B.
Answer 18/36
C.
20/38
D.
2/36
Select a first-year college student at random and ask what his or her academic
rank was in high school. Here are the probabilities, based on proportions from
a large sample survey of first-year students:
Question Rank: Top 20% Second 20% Third 20% Fourth 20%
Probability: 0.44 0.26 0.23 0.06 0.01
Lowest 20%
What is the probability that a first-year student was in the top 40 percent in
high school?
A.
Answer
0.70
B.
0.60
C.
0.44
D.
0.26
Select a first-year college student at random and ask what his or her academic
rank was in high school. Here are the probabilities, based on proportions from
a large sample survey of first-year students:
Question
Rank: Top 20% Second 20% Third 20% Fourth 20%
Probability: 0.44 0.26 0.23 0.06 0.01
Lowest 20%
What is the probability that a randomly chosen first-year college student was
not in the top 20 percent of his or her high school class?
A.
0.56
B.
Answer 0.99
C.
0.44
D.
0.07
There are 36 possible outcomes when you roll two casino dice and record upfaces in order (first die, second die).
Question
What is the probability that the sum of the spots on up-faces is 11? (Hint:
Examine Figure 18.1 on pg. 398 of the book.)
A.
0.056
Answer B.
0.065
C.
0.076
True or false: The following assignment of probabilities to individual
outcomes is legitimate:
Question
When a coin is spun, P (H) = 0.55 and P(T) = 0.45.
[Hint: Recall the precise definition of "legitimate".]
Answer
True
False
True or false: The following assignment of probabilities to individual
outcomes is legitimate:
When two coins are tossed, P(HH) = 0.4, P(HT) = 0.4, P(TH) = 0.4,
Question and P(TT) = 0.4.
[Hint: Recall the precise definition of "legitimate".]
Answer
True
False
Government data assign a single cause for each death that occurs in the United
States. The data show that the probability is 0.27 that a randomly chosen death
Question was due to heart disease, and is 0.23 that it was due to cancer.
What is the probability that a death was due to either heart disease or cancer?
A.
0.27
B.
0.23
Answer C.
0.04
D.
0.50
Question
A couple plans to have three children. There are 8 possible arrangements of
girls and boys. For example, GGB means the first two children are girls and
the third child is a boy.
Suppose all eight possible arrangements are equally likely. What is the
probability of any one of these arrangements?
A.
1/2
B.
Answer 1/4
C.
1/8
A Gallup poll on Presidents Day 2008 interviewed a random sample of 1007
adult Americans. They were asked which former president they would like to
bring back as the next president if they could. Here are the results:
Outcome
John F. Kennedy
Ronald Reagan
Abraham Lincoln
Someone else
Question
Probability
0.23
0.22
0.10
?
These proportions are probabilities for the random phenomenon of choosing
an adult American at random and asking her or his opinion.
What must be the probability that the person chosen selects someone other
than John F. Kennedy, Ronald Reagan, or Abraham Lincoln?
A.
0.22
B.
0.23
Answer C.
0.12
D.
0.45
CHAPTER 20 HOMEWORK
Female Asian beetles have this probability model for their number of female
offspring:
Question
Offspring:
0
1 2
Probability: 0.2 0.3 0.5
What is the expected number of female offspring?
A.
1
B.
Answer 1.3
C.
2
D.
0.5
Female Asian beetles have this probability model for their number of female
offspring:
Offspring:
0
1 2
Question Probability: 0.2 0.3 0.5
True or false: The population should grow if the expected number of female
offspring is greater than 1 and die out if the expected value is less than 1.
Answer
True
False
Suppose you sell insurance to a 21-year-old friend. The probability that a man
aged 21 will die in the next year is about 0.0015. You decide to charge $2000
for a policy that will pay $1,000,000 if your friend dies.
Question
What is your expected profit on this policy?
A.
$500
B.
$2000
Answer C.
$150
D.
$497
Suppose you sell insurance to a 21-year-old friend. The probability that a man
aged 21 will die in the next year is about 0.0015. You decide to charge $2000
for a policy that will pay $1,000,000 if your friend dies.
Question
Why would you be foolish to sell a single such policy only to your friend?
A.
The law of large numbers will not apply if only a single policy is sold.
Answer
B.
You have a 50-50 chance of either gaining a moderate amount of money, or
losing a great deal of money.
C.
It is never wise to mix friendship with business.
Assume the following distribution for the number of people in American
families in 2009 (and assume the probability of more than 7 people in a family
is negligible):
Family size:
2
3
4
5
6
7
Question
Proportion:
0.45 0.22 0.19 0.09 0.03 0.02
What is the expected value for family size?
A.
2
B.
3
Answer
C.
3.09
D.
2.50
The distribution of grades in a large chemistry class is as follows:
Question Grade:
Probability:
A
B
C
D
F
0.1 0.4 0.3 0.1 0.1
Convert the grades to a numerical scale using A = 4, B= 3, C = 2, D = 1, F =
0. Calculate the expected value.
A.
3
B.
Answer 2.3
C.
2.5
D.
2.1
CHAPTER 21 HOMEWORK
A college president says, "99% of the alumni support my firing of Coach
Boggs." You contact a simple random sample of 200 of the college's 15000
living alumni and find that 66 of those support firing the coach.
Question
What population does the inference concern here?
A.
The football team
B.
Answer The college president
C.
All coaches
D.
The college's alumni
A college president says, "99% of the alumni support my firing of Coach
Boggs." You contact a simple random sample of 200 of the college's 15000
living alumni and find that 66 of those support firing the coach.
Question
What is the numerical value of the sample proportion?
A.
0.99
B.
0.66
Answer
C.
0.33
D.
0.0013
Harley-Davidson motorcycles make up 28% of all the motorcycles registered
in the U.S. You plan to interview a simple random sample of 600 motorcycle
Question
owners. What is the sampling distribution of the proportion of your sample
who own Harleys?
Answer
A.
approximately normal, with mean 0.28 and standard deviation 0.0183
B.
approximately normal, with mean 0.28 and standard deviation 0.0003
C.
approximately normal, with mean 0.0114 and standard deviation 0.0183
D.
approximately normal, with mean 0.0114 and standard deviation 0.0003
Question
An October 2011 Gallup Poll asked a sample of 1005 American adults
whether they thought there should be a law that would ban the possession of
handguns except by the police and other authorized persons. Only 261 of the
respondents thought there should be such a law.
What is the interpretation of the population proportion p for this poll?
A.
The proportion of those sampled who believe there should be this type of law.
B.
Answer
The proportion of all American adults who believe there should be this type of
law.
C.
The proportion of all American men who believe there should be this type of
law.
D.
The proportion of all American police who believe there should be this type of
law.
Question
An October 2011 Gallup Poll asked a sample of 1005 American adults
whether they thought there should be a law that would ban the possession of
handguns except by the police and other authorized persons. Only 261 of the
respondents thought there should be such a law.
Find a 95% confidence interval for p, the relevant population proportion.
A.
(0.218, 0.301)
B.
Answer (0.232, 0.287)
C.
(0.259, 0.260)
D.
(0.1005, 0.261)
An October 2011 CBS News poll asked 1012 randomly selected American
adults whether they "opposed allowing the children of illegal immigrants to
attend state college at the lower tuition rate of state residents." Of those
sampled, 688 said they did oppose letting them attend at the lower tuition rate.
Question
Give a 95% confidence interval for the population proportion who oppose
letting them attend at the lower tuition rate.
A.
(0.642, 0.718)
Answer
B.
(0.651, 0.709)
C.
(0.679, 0.680)
D.
(0.648, 0.711)
An October 2011 CBS News poll asked 1012 randomly selected American
adults whether they "opposed allowing the children of illegal immigrants to
attend state college at the lower tuition rate of state residents." Of those
sampled, 688 said they did oppose letting them attend at the lower tuition rate.
Question
What is the parameter p is this setting?
A.
The proportion of all American adults who oppose allowing the children of
illegal immigrants to attend state college.
B.
The proportion of the sampled American adults who oppose allowing the
children of illegal immigrants to attend state college at the lower tuition rate of
state residents.
Answer
C.
The proportion of all American immigrants who oppose allowing the children
of illegal immigrants to attend state college at the lower tuition rate of state
residents.
D.
The proportion of all American adults who oppose allowing the children of
illegal immigrants to attend state college at the lower tuition rate of state
residents.
Consider a group of 27 patients in an experiment who received a placebo. At
the beginning of the study, the researchers measured the seated systolic blood
pressure of these 27 patients. The sample mean was 114.9 and the sample
standard deviation was 9.3.
Question
Find a 95% confidence interval for the mean blood pressure of the population
from which the patients were recruited.
A.
(111.3, 118.5)
B.
Answer (113.2, 116.6)
C.
(114.2, 115.6)
D.
(112.3, 117.5)
CHAPTER 22 HOMEWORK
At one large university, 78% of all students who entered in 2004 graduated
within six years. Out of a sample of 190 students on athletic scholarships, 137
of them graduated within six years. We are investigating whether there is
evidence that the percentage of athletes who graduate within six years is less
than 78%.
Question
What are the null and alternative hypotheses?
A.
H0: p > 0.78, Ha: p < 0.78
B.
Answer H0: p = 0.78, Ha: p < 0.78
C.
H0: p = 0.78, Ha: p =/= 0.78
D.
H0: p > 0.78, Ha: p = 0.78
At one large university, 78% of all students who entered in 2004 graduated
within six years. Out of a sample of 190 students on athletic scholarships, 137
of them graduated within six years. We are investigating whether there is
evidence that the percentage of athletes who graduate within six years is less
Question than 78%.
In words, what is the parameter p in this setting?
A.
The proportion of all students who graduate within six years.
B.
The proportion of all sampled athletes who graduate within six years.
Answer
C.
The proportion of all students on athletic scholarships who graduate within six
years.
D.
137 out of 190 students.
Question
At one large university, 78% of all students who entered in 2004 graduated
within six years. Out of a sample of 190 students on athletic scholarships, 137
of them graduated within six years. We are investigating whether there is
evidence that the percentage of athletes who graduate within six years is less
than 78%.
The P-value is 0.025. If our significance level is 0.05, what is the correct
conclusion?
A.
The proportion of all students on athletic scholarship who graduate within six
years is less than 0.78.
B.
The proportion of all students on athletic scholarship who graduate within six
Answer years is greater than 0.78.
C.
The proportion of all students on athletic scholarship who graduate within six
years is equal to 0.78.
D.
The proportion of all students on athletic scholarship who graduate within six
years is equal to 0.025.
Our statistical software has a random number generator that is supposed to
produce numbers scattered at random between 0 and 1. If this is true, the
Question
population of generated numbers has a mean of 0.5. A command to generate
100 random numbers gives results with sample mean 0.536 and sample
standard deviation 0.312. We are investigating whether the mean of the
population of numbers produced differs from 0.5.
What are the null and alternative hypotheses?
A.
H0: mu =/= 0.5, Ha: mu = 0.5
B.
Answer H0: mu = 0.5, Ha: mu =/= 0.5
C.
H0: mu = 0.5, Ha: mu > 0.5
D.
H0: mu = 0.5, Ha: mu < 0.5
Our statistical software has a random number generator that is supposed to
produce numbers scattered at random between 0 and 1. If this is true, the
population of generated numbers has a mean of 0.5. A command to generate
100 random numbers gives results with sample mean 0.536 and sample
standard deviation 0.312. We are investigating whether the mean of the
Question
population of numbers produced differs from 0.5.
The P-value is 0.249. If our significance level is 0.05, what is our conclusion?
A.
The mean of the population of numbers produced differs from 0.5.
Answer B.
The mean of the population of numbers produced definitely does not differ
from 0.5.
C.
The mean of the population of numbers produced is greater than 0.5.
D.
The mean of the population of numbers produced may not differ from 0.5.
In 2006, 75.9% of first-year college students used the Internet frequently for
research or homework. Administrators at a large state university believe their
students use the Internet more frequently than students in 2006. Out of a
sample of 200 of this university's first-year students, 168 of them said they
used the Internet frequently for research or homework. We investigate
whether this is strong enough evidence to say that the proportion of students at
Question
this university who use the Internet frequently for research or homework is
larger than the 2006 national value.
What are the null and alternative hypotheses?
A.
H0: p = 0.759, Ha: p =/= 0.759
B.
H0: p = 0.759, Ha: p < 0.759
Answer
C.
H0: p = 0.759, Ha: p > 0.759
D.
H0: p > 0.759, Ha: p = 0.759
In 2006, 75.9% of first-year college students used the Internet frequently for
research or homework. Administrators at a large state university believe their
students use the Internet more frequently than students in 2006. Out of a
sample of 200 of this university's first-year students, 168 of them said they
used the Internet frequently for research or homework. We investigate
whether this is strong enough evidence to say that the proportion of students at
Question this university who use the Internet frequently for research or homework is
larger than the 2006 national value.
The P-value is 0.0037. If we have a significance level of 0.01, then what is
our conclusion?
A.
The proportion of students at this university who use the Internet frequently
for research or homework is larger than the 2006 national value.
B.
Answer
The proportion of students at this university who use the Internet frequently
for research or homework is smaller than the 2006 national value.
C.
The proportion of students at this university who use the Internet frequently
for research or homework is equal to the 2006 national value.
D.
If the proportion of students at this university who use the Internet frequently
for research or homework is 0.759, then it would be very likely to see a
sample proportion like 168/200 or larger.
In 2006, 75.9% of first-year college students used the Internet frequently for
research or homework. Administrators at a large state university believe their
students use the Internet more frequently than students in 2006. Out of a
Question
sample of 200 of this university's first-year students, 168 of them said they
used the Internet frequently for research or homework. We investigate
whether this is strong enough evidence to say that the proportion of students at
this university who use the Internet frequently for research or homework is
larger than the 2006 national value.
In words, what is the parameter p in this setting?
A.
168 out of 200 students
B.
The proportion of all first-year students at all American universities who use
the Internet frequently for research or homework
Answer
C.
The proportion of sampled first-year students at this university who use the
Internet frequently for research or homework
D.
The proportion of all first-year students at this university who use the Internet
frequently for research or homework
CHAPTER 14 HOMEWORK
An article published on February 2, 2008 in the Columbus Dispatch reported a
study on distances students lived from campus and average GPA. Here is a
summary of the results.
Residence Avg. GPA
Residence hall 3.33
Walking distance 3.16
Near campus, long walk or short drive 3.12
Question
Within the country, not near campus 2.97
Outside the country 2.94
Answer
Identify the statement that is correct about the association between the two
variables: distance a student lives from campus, and GPA.
A.
The association between the two variables is positive.
B.
The association between the two variables is approximately equal to 0.
C.
The association between the two variables is negative.
The scatterplot displays the calories and sodium content in 17 brands of meat
hot dogs.
Question
Select the most appropriate option. Point A can be considered unusual
because:
A.
Answer It is below average in sodium.
B.
It is below average in both calories and sodium.
C.
It is below average in calories.
The gas mileage of an automobile first increases and then decreases as the
speed increases. Suppose that this relationship is very regular, as shown by the
following data on speed (miles per hour) and mileage (miles per gallon):
Speed(x) Mileage(y)
30 20
40 24
50 26
60 24
70 20
Consider the given scatterplot showing the relationship between speed and
mileage.
Question
Identify the statement that correctly explains why the correlation is 0 even
though there is a strong relationship between speed and mileage?
A.
The relationship between speed and mileage is inconsistent.
Answer
B.
The relationship between speed and mileage is non-linear.
C.
The sample size of 5 is too small to identify the characteristic of the
relationship between two variables.
Metabolic rate, the rate at which the body consumes energy, is important in
studies of weight gain, dieting, and exercise. The data on the lean body mass
and resting metabolic rate for 12 women and 7 men who are subjects in a
study of dieting is displayed.
Subject Sex Mass (lb) Rate (cal)
1 M 136.4 1792
2 M 138.4 1666
3 F 79.4 995
4 F 120.1 1425
5 F 106.7 1396
6 F 92.4 1418
7 M 104.3 1362
Question 8 F 111.3 1502
9 F 92.4 1256
10 M 107.1 1614
11 F 88.7 1189
12 F 72.8 913
13 M 114.2 1460
14 F 93.3 1124
15 F 75.9 1052
16 F 112.4 1347
17 F 90.6 1204
18 M 114.1 1867
19 M 103.2 1439
Lean body mass, given pounds, is a person's weight leaving out all
fat. Metabolic rate is measured in calories burned per 24 hours.
How would the correlation between body mass and metabolic rate change if
the body mass is represented in kilograms (1 kilogram = 2.2 pounds)?
A.
The correlation would be divided by 2.2.
B.
Answer The correlation would be multiplied by 2.2.
C.
The correlation would not change.
Professor Moore swims 2000 yards regularly in a vain attempt to undo middle
age. His timings in minutes and his pulse rate in beats per minute after
swimming for 23 sessions in the pool are displayed in the following table.
Time(x) Pulse Rate(y)
34.12 152
35.72 124
34.72 140
34.05 152
34.13 146
35.72 128
Question 36.17 136
35.57 144
35.37 148
35.57 144
35.43 136
36.05 124
34.85 148
34.70 144
34.75 140
33.93 156
34.60 136
34.00
34.35
35.62
35.68
35.28
35.97
148
148
132
124
132
159
Suppose that the time had been recorded in seconds. For example, 34.12
minutes would be recorded as 2047 seconds. How would the value of r
change?
A.
The value of r would not change.
B.
Answer
The value of r would be greater than the value of r calculated with time
recorded in minutes.
C.
The value of r would be smaller than the value of r calculated with time
recorded in minutes.
Question
You might expect the correlation between the cost of an Internet supplier
service and the download speed provided by the service to be:
A.
Answer
A substantial positive correlation
B.
A small correlation
C.
A substantial negative correlation
Professor Moore swims 2000 yards regularly in a vain attempt to undo middle
age. His timings in minutes and his pulse rate in beats per minute after
swimming for 23 sessions in the pool are displayed in the following plot:
Question
Consider the following data:
Mean(x) = 35.059
Mean(y) = 140.043
Sx = 0.7287
Sy = 9.4699
The value of correlation(r) = -0.746. Consider the scatterplot showing the
relationship between time and pulse rate.
The correlation(r) = -0.746 is reasonable because the scatterplot shows:
A.
A moderately weak negative linear association.
Answer B.
A moderately strong positive linear association.
C.
A moderately strong negative linear association.
A college newspaper interviews a psychologist about the student ratings of the
teaching of faculty members. The psychologist says, “The evidence indicates
that the correlation between the research productivity and teaching rating of
faculty members is close to zero.” The paper reports this as “Professor
Question McDaniel said that good researchers tend to be poor teachers, and vice versa.”
The newspaper’s report is wrong.
Which of the following statements correctly explains the newspaper
interpretation of the professor’s comment?
A.
The newspaper interpreted zero correlation as a non-linear relationship.
B.
Answer The newspaper interpreted zero calculation as no relationship.
C.
The newspaper interpreted zero correlation as a negative relationship.
Consider the following data:
X Y
1 10
2 3
3 3
4 5
Question
9 9
10 11
Consider the given scatterplot:
What feature of the data is responsible for reducing the correlation to
approximately 0.5 despite a strong straight-line association between x and y in
most observations?
A.
Low number of observations
Answer B.
Presence of outlier
C.
Positive direction of correlation
For centuries, people have associated intelligence with the brain size. A recent
study used magnetic resonance imaging to measure the brain size of several
individuals. The IQ and brain size (in units of 10,000 pixels) of six individuals
are displayed in the following table:
Brain size IQ
Question
100 140
90 90
95 100
92 135
88 80
106
103
True or false: Brain size is the explanatory variable, and IQ is the response
variable.
True
False
Answer
A college newspaper interviews a psychologist about the student ratings of
the teaching of faculty members. The psychologist says, “The evidence
indicates that the correlation between the research productivity and teaching
rating of faculty members is close to zero.” The paper reports this as
Question “Professor McDaniel said that good researchers tend to be poor teachers, and
vice versa.” The newspaper’s report is wrong.
Identify the statement that states the correct interpretation of the professor’s
comment.
A.
The research productivity and the teaching ability have a positive relationship.
Answer B.
The research productivity and the teaching ability are not (linearly) related
C.
The research productivity and the teaching ability have a linear relationship.
A scatterplot of school GPA versus IQ score for all 78 seventh-grade students
in a rural Midwest school is given. Points A, B, and C are outliers.
Question
If three outliers are removed from the scatterplot, the correlation r:
A.
Increases
Answer B.
Remains unchanged
C.
Decreases