# Quiz 6: Using Probability to Make Decisions About Data

Psychology

Q 1Q 1

What is the essence of all inferential statistics?
A)Making inferences about the characteristics of samples
B)Making sure you choose a sample representing the population
C)Knowing the characteristics of the population
D)Using sample data to make statements about the scores and relationships in the population

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D

Q 2Q 2

How is the relative frequency of an event defined?
A)Since the z-value does not fall within the region of rejection, we should not conclude that this sample mean represents some other population
B)The average number of times an event occurs in the population of events
C)The proportion of times an event occurs in the population of events
D)The proportion of times all events occur

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Multiple Choice

C

Q 3Q 3

An event's relative frequency in the population equals
A)100%.
B)the average number of times an event occurs in the population.
C)the odds of the event.
D)the probability of the event.

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D

Q 4Q 4

Which of the following best describes knowing the relative frequency of every possible event in a population?
A)A probability distribution
B)A population distribution
C)A frequency distribution
D)A sample distribution

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Multiple Choice

Q 5Q 5

When rolling a pair of fair dice, the probability of rolling a total point value of "7" is 0.17.If you rolled a pair of dice 1,000 times and the point value of "7" appeared 723 times, what would you probably conclude?
A)This is not so unlikely as to make you doubt the fairness of the dice.
B)Although not impossible, this outcome is so unlikely the fairness of these dice is questionable.
C)Since the total point value of "7" has the highest probability of any event in the sampling distribution, this is an extremely likely outcome.
D)It is impossible for this to happen if the dice are fair.

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Multiple Choice

Q 6Q 6

Which of the following accurately describes a theoretical probability distribution?
A)A theoretical model based on how we assume nature distributes events in the population
B)A theoretical model based on the events in a sample
C)The computed relative frequency of events in a set of samples that were actually drawn
D)The relative frequencies of some of the events in a sampling distribution

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Multiple Choice

Q 7Q 7

What do we call the portion of the sampling distribution in which values are considered too unlikely to have occurred by chance?
A)Region of criterion value
B)Region of critical value
C)Region of rejection
D)Critical value

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Multiple Choice

Q 8Q 8

What is the purpose of the critical value?
A)To define the minimum absolute z-value required for a sample to be in the region of rejection.
B)To define the minimum absolute z-value required for a sample to be out of the region of rejection.
C)To determine the likelihood that the population mean was obtained by chance.
D)To determine the value of z needed to conclude that the population mean was obtained by chance.

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Multiple Choice

Q 9Q 9

What is the critical value?
A)The outer end of the region of rejection
B)The inner edge of the region of rejection
C)The absolute value of the entire region of rejection
D)The area under the curve in the region of rejection

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Multiple Choice

Q 10Q 10

Which of the following is correct regarding means falling within the region of rejection when the critical values are
A)It is likely they represent the population under study.
B)They have a high relative frequency.
C)They occur with a probability of 95%.
D)They occur with a probability of 5%.

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Multiple Choice

Q 11Q 11

Which of the following is not true of the criterion?
A)The criterion is the probability defining samples as unlikely.
B)Samples meeting the criterion occur more than 5% of the time.
C)Behavioral researchers usually use 0.05 as their criterion probability.
D)Sample means occurring with a probability less than that of the criterion probability are likely to represent some other population.

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Multiple Choice

Q 12Q 12

What can we conclude when the absolute value of a z-score for a sample mean is larger than the critical value?
A)The random selection procedure was conducted improperly.
B)The sample mean is reasonably likely to have come from the given population by random sampling.
C)The sample mean represents the particular raw score population on which the sampling distribution is based.
D)The sample mean does not represent the particular raw score population on which the sampling distribution is based.

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Multiple Choice

Q 13Q 13

What can you conclude about a sample mean falling within the region of rejection?
A)The sample probably represents some population other than the one on which the sampling distribution was based.
B)The sample represents the population on which the sampling distribution was based.
C)Another sample needs to be collected.
D)The sample should have come from the given population.

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Multiple Choice

Q 14Q 14

A study about the college aptitude of seniors at North City High School has resulted in a sample mean with a corresponding z-score of −2.00.If the critical value for the region of rejection is what is the correct conclusion?
A)Since the z-value falls within the region of rejection, we should conclude this sample mean likely represents some other population.
B)Since the z-value does not fall within the region of rejection, we should not conclude this sample mean represents some other population.
C)Since the z-value falls within the region of rejection, we should not conclude this sample mean represents some other population.
D)Since the z-value does not fall within the region of rejection, we should conclude this sample mean likely represents some other population.

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Multiple Choice

Q 15Q 15

Which of the following is not a step when deciding whether or not a population is being represented?
A)Set up the sampling distribution.
B)Compute the z-score.
C)Compute the mode.
D)Compare the z-score to the critical value.

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Multiple Choice

Q 16Q 16

When a z-score is not in the region of rejection, we should
A)reject the idea that random chance produced a sample representing the population poorly.
B)conclude with the idea that sample scores and the raw score population are similar enough to be called identical.
C)not reject the idea that the sample represents the raw score population.
D)reject the idea that the sample represents the raw score population.

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Multiple Choice

Q 17Q 17

A study about the college aptitude of seniors at South City High School has resulted in a sample mean with a corresponding z-score of +1.89.If the critical value for the region of rejection is what is the correct conclusion?
A)Since the z-value falls within the region of rejection, we should conclude this sample mean likely represents some other population.
B)Since the z-value does not fall within the region of rejection, we should not conclude this sample mean represents some other population.
C)Since the z-value falls within the region of rejection, we should not conclude this sample mean represents some other population.
D)Since the z-value does not fall within the region of rejection, we should conclude this sample mean likely represents some other population.

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Multiple Choice

Q 18Q 18

When +1.645 is used as the critical value instead of ±1.96 and the criterion probability is 0.05 in both cases,
A)the total probability of the region of rejection is decreased.
B)the total probability of the region of rejection is increased.
C)the region of rejection is all placed in the positive z-distribution tail.
D)the region of rejection is all placed in the negative z-distribution tail.

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Multiple Choice

Q 19Q 19

When does sampling error occur?
A)When a sample statistic is not equal to the population parameter as a result of nonchance factors
B)When a sample statistic is not equal to the population parameter as a result of chance factors
C)When there has been an error in calculating the standard error of the mean
D)When there has been an error in calculating the sample mean

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Multiple Choice

Q 20Q 20

tries to ensure that every member of a given population has an equal chance of inclusion in a given study.
A)Random selection
B)Random assignment
C)Sampling
D)Probability

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Q 21Q 21

When you see the symbol "p," it refers to
A)probability.
B)population.
C)percentile.
D)power.

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Q 22Q 22

The range of probabilities
A)must be between 0 and 1.
B)is limitless.
C)is between 0 and 100.
D)must be at least 0, but it has no higher limit.

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Multiple Choice

Q 23Q 23

Suppose you flip a fair coin five times and get a "heads" each time.Your friend insists that your next flip certainly will come up as "tails." Is your friend correct?
A)No, though the gambler's fallacy makes us think this, it is not a guarantee that the next flip will be "tails."
B)Yes, due to the gambler's fallacy.
C)No, it probably is impossible to get "tails" with this particular coin.
D)While you should get "tails," you're probably more likely to get "heads."

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Multiple Choice

Q 24Q 24

Suzy is about to pick a cookie from a cookie jar.The cookie jar contains 4 chocolate chip, 3 vanilla, 2 ginger snap, and 1 sugar cookie.What is the probability that Suzy will not pick a vanilla cookie?
A).7
B).3
C)7
D)3

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Multiple Choice

Q 25Q 25

Consistent with the basic premise of a representative sample, if a given population consists of 60% women, your sample should have
A)40% men.
B)no less than 60% women.
C)an equal number of men and women.
D)whatever composition of men and women that you can find.

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Q 26Q 26

Your professor told the class that, typically, 20% of the class receives As, 20% Bs, 35% Cs, 10% Ds, and 15% Fs.What is the probability the student sitting next to you will receive an A or an F? Put your answer in the form of a proportion.

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Q 28Q 28

What is the probability of getting a sample mean between 500 and 520 if the population mean is 500 and the standard deviation of the sampling distribution the standard error of the mean) is 20?

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Q 31Q 31

If your critical value is ±1.96 and your z-value is -2.44, do you reject the sample mean represents the underlying population or not?

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Q 32Q 32

An article in a professional journal reports the zscore for the study's sample mean was -1.4.The authors also reported their sample mean was 97 with a sample size of 49 and the population mean was 102.However, they did not give the population standard deviation.What was their population standard deviation?

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Q 33Q 33

If the population variance is 36, what is the standard error of the mean for a sample size of 144?

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Q 35Q 35

In a test of physical fitness, a group of men ages 65 and older from a local retirement community were told to do as many sit-ups as they could.It is known the population mean is 20 with The scores for the men from the retirement community are given below.Use a two-tailed rejection region with a total area of 0.05.What is the sample mean?

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Q 36Q 36

In a test of physical fitness, a group of men ages 65 and older from a local retirement community were told to do as many sit-ups as they could.It is known the population mean is 20 with The scores for the men from the retirement community are given below.Use a two-tailed rejection region with a total area of 0.05.What is the standard error of the mean?

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Q 37Q 37

In a test of physical fitness, a group of men ages 65 and older from a local retirement community were told to do as many sit-ups as they could.It is known the population mean is 20 with The scores for the men from the retirement community are given below.Use a two-tailed rejection region with a total area of 0.05.What is the z- value?

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Q 38Q 38

In a test of physical fitness, a group of men ages 65 and older from a local retirement community were told to do as many sit-ups as they could.It is known the population mean is 20 with The scores for the men from the retirement community are given below.Use a two-tailed rejection region with a total area of 0.05.What critical value should you use?

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Q 39Q 39

The mean of the population is 200 on a test measuring math skills of middle school students.The variance is
.The test scores for the students in Mr.Petri's class at Suburban Middle School are given below.Use a
rejection region with a probability of 5% only in the upper tail.What is the sample mean?

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Q 40Q 40

The mean of the population is 200 on a test measuring math skills of middle school students.The variance is
.The test scores for the students in Mr.Petri's class at Suburban Middle School are given below.Use a
rejection region with a probability of 5% only in the upper tail.What is the standard error of the mean?

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Q 41Q 41

The mean of the population is 200 on a test measuring math skills of middle school students.The variance is
.The test scores for the students in Mr.Petri's class at Suburban Middle School are given below.Use a
rejection region with a probability of 5% only in the upper tail.What is the z-value?

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Q 42Q 42

The mean of the population is 200 on a test measuring math skills of middle school students.The variance is
.The test scores for the students in Mr.Petri's class at Suburban Middle School are given below.Use a
rejection region with a probability of 5% only in the upper tail.What critical value should you use?

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Q 43Q 43

The mean of the population is 200 on a test measuring math skills of middle school students.The variance is
.The test scores for the students in Mr.Petri's class at Suburban Middle School are given below.Use a
rejection region with a probability of 5% only in the upper tail.What should you conclude?

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Q 44Q 44

The introductory biology class at State University is conducting a study of water quality in their local community.The population mean of a certain beneficial bacteria found in drinking water 100, with The bacteria counts from the community are given below.Use a two-tailed rejection region with a total area of 0.01.What is the standard error of the mean?

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Q 45Q 45

The introductory biology class at State University is conducting a study of water quality in their local community.The population mean of a certain beneficial bacteria found in drinking water 100, with The bacteria counts from the community are given below.Use a two-tailed rejection region with a total area of 0.01.What critical value should you use?

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Q 46Q 46

A group of students were tested using a new software program.The researchers observed a sample mean of with a sample size of N = 20.They know the population mean is and , so they use and a one-tailed test to determine if their sample is greater than the known population mean.

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Q 47Q 47

At a carnival game, you'll win a prize if you pick a rubber duck out of a pool that has a red dot on the bottom.If only 3 ducks out of 95 present have such a dot, what is your probability of winning a prize?

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Q 48Q 48

Suppose you flip a fair coin five times.Which of the following combinations is most likely to occur?
HHHHH HTHTH

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Q 49Q 49

Suppose you are doing a poll of various attitudes for students at your college.You are especially interested in having an accurate representative sample based on student's geographical home area within the United States.Suppose at your college, 45% hail from the Northeast, 30% originate from the Midwest, 15% are from the West, and 10% are from the South.If you are looking to have a sample of 200 individuals, who should be included in order to have a representative sample?

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Q 50Q 50

Professor White felt that he had a representative sample--but he starting to wonder if he really did.Briefly note what might make Professor White feel this way.

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Q 51Q 51

What are the two fundamental reasons why a sample mean may differ from a particular population mean?

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Q 54Q 54

What are the three basic steps used to ascertain whether a sample represents a given population?

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