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11/10/2018 Revisar envio do teste: Avaliação - Statistics 3 – ...
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Pergunta 1
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This is correct. This is the only incorrect statement.
 A 2015 CNN Money article provided the following information about the social class distribution of
U.S. adults.
 
 
Apply probability rules in order to find the likelihood of an event
"Fill in the blank" question: select the correct answer.
Two U.S. adults are chosen at random.Let A be the event that the first adult belongs to
the Middle ClassLet B be the event that the second adult belongs to the Lower class.
Complete the following sentences:
Events A and B are
.Events A and B are
 
Independent
Independent
This is correct. Since the two chosen are from a large population (of all U.S.
adults), the social class of the first adults has no effect on the social class of
the second chosen adult.
Pergunta 2
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A family eats out twice a month – once during the first week of the month and once
during the third week of the month, in one of the three local restaurants: R1, R2, or R3.
Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during
the first week of the month and in R2 during the third week of the month. It is possible
for the family to eat at the same restaurant both on the first week and on the third week
of the month.
Determine the sample space of a random experiment and identify which outcomes are
included in a particular event
"multiple choice" question: select the correct answer.
Which of the following is the correct sample space in this case?
 
S= { (R1, R1) (R2, R2) (R3, R3) (R1, R2) (R2, R1) (R1, R3) (R3, R1)
(R2, R3) (R3, R2) }
S= { (R1, R1) (R2, R2) (R3, R3) (R1, R2) (R2, R1) (R1, R3) (R3, R1)
(R2, R3) (R3, R2) }
This is correct.
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11/10/2018 Revisar envio do teste: Avaliação - Statistics 3 – ...
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Pergunta 3
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Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given
situation and apply it to determine likelihoods.
 "multiple choice" question: select the correct answer. Suppose that the average number of defects
in the sample of n=225cars was found to be x̅=5.1. What is the z-score of this average?
 
3
3
This is correct. Z=x¯ −μσn√=5.1−3.67.5225√=1.50.5=3
Pergunta 4
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The weekly cost of maintenance and repairs for a company has a normal distribution with mean
μ=$5500 and standard deviation σ=$400.
 Note: For questions 19 and 20 you will need to use the Normal Table linked here
 
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
If $6200 is budgeted for the next week, what is the probability that the cost will exceed
the budgeted amount?
 
.0401
.0401
This is correct.
P(X>6200)=[z=6200−5500400=1.75]=P(Z>1.75)=
[table]=1−.9599=0401
 
Pergunta 5
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Understand how relative frequency can be used to estimate the probability of an event
and apply this approach in practice.
"multiple choice" question: select the correct answer.
It was estimated that in a certain population roughly 5% carry the HIV virus. A few
years later a researcher wanted to confirm this has not changed. If we let V be the event
that a randomly chosen person from this population carries the HIV virus, which of the
following will provide the most convincing evidence that indeed P(V) is roughly 0.05?
 
40 randomly chosen individuals from this population are tested and 2 of
them are found to carry the HIV virus.
2000 randomly chosen individuals from this population are tested and
102 of them are found to carry the HIV virus.
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11/10/2018 Revisar envio do teste: Avaliação - Statistics 3 – ...
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Pergunta 6
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A lot of research is conducted on the sleeping habits of U.S. adults. One study reported that X, the
amount of sleep per night of U.S. adults follows a normal distribution with mean μ=7.5 hours and
standard deviation σ=1.2 hours.
 
P(8.5<X≤9.5)
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
Using the Standard Deviation Rule, what is the probability that a randomly chosen U.S.
adult sleeps more than 8.7 hours per night?
 
0.84
0.16
Pergunta 7
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Understand how probability quantifies uncertainty and relate the probability of an event
to the likelihood of the event occurring.
"multiple choice" question: select the correct answer.
Which of the following is true regarding a probability of an event P(A)?
 
P(A)≤1
0≤P(A)≤1
Pergunta 8
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
The National Survey on Drug Use and Health also reported that 21% of males in the
same age group (12-20) are binge drinkers.
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Suppose that in addition to the 10 randomly chosen females, a random sample 10 males
from the same age group is chosen (to a total of 20).
Let the random variable Y be the total number of males and females (out of 20) who are
binge drinkers.
Which of the following is true regarding the random variable Y?
Y has a binomial distribution with n=20 and p=.18
Y has a binomial distribution with n=20 and p=.18
This is correct. p=0.15 for 10 of the trials (the 10 females) and p=0.21
for the other 10 trials (the 10 males).
Pergunta 9
Resposta Selecionada: 
Resposta Correta: 
Feedback da
resposta:
This is correct. This is the only incorrect statement.
 A 2015 CNN Money article provided the following information about the social class distribution of
U.S. adults.
 
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Two U.S. adults are chosen at random.
Which of the following is the probability that first chosen is Middle Class and the
second chosen is Lower Class? In other words, which of the following is P(A and B),
where events A and B are as defined in Question #8.
 
.50 * .29
.50 * .29
This is correct. P(A and B) = [A, B independent] = P(A) * P(B) =
.50 * .29
Pergunta 10
A family eats out twice a month – once during the first week of the month and once during the
third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome
(R3, R2) denotes that on a given month the family eats in R3 during the first week of the month
and in R2 during the third week of the month. It is possible for the family to eat at the same
restaurant both on the first week and on the third week of the month.
Apply probability rules in order to find the likelihoodof an event
"multiple choice" question: select the correct answer.
Let B be the event that on a given month the family eats in R1 at least once.In context,
the complement of event B, ‘Not B’ is the event that:
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11/10/2018 Revisar envio do teste: Avaliação - Statistics 3 – ...
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Quinta-feira, 11 de Outubro de 2018 13h59min28s BRT
Resposta Selecionada: 
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in a given month, the family eats at R1 twice
in a given month, the family eats at R1 twice
This is correct.