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```Pergunta 1
0 em 1 pontos
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
Use the normal distribution as an approximation to the binomial distribution
"multiple choice" question: select the correct answer.
Which of the following is the correct justification for reliably using the normal
approximation for X?

Resposta

n = 1600 ≥ 30
Resposta Correta:
Both np = 1600 * 0.1 = 160 ≥ 10 and n(1 - p) = 1600 * 0.9
= 1440 ≥ 10

Pergunta 2
0 em 1 pontos

The following three probability histograms represent the probability distributions of
the random variables X, Y, and W.
As is evident from the probability histograms, the mean of all three random variables
is 5.
Find the mean and variance of a discrete random variable, and apply these
concepts for solving real world problems.
"multiple choice" question: select the correct answer.
Which of the three random variables has the largest standard deviation?

Resposta Correta:
X

Pergunta 3
1 em 1 pontos

An epidemiological study investigated the prevalence of two contagious
diseases ( Disease 1 and Disease 2) in the U.S.
Let A be the event that an individual contracts Disease 1
Let B be the event that an individual contracts Disease 2
Understand the reasoning behind the concept of conditional probability,
calculate conditional probabilities and interpret them.
"multiple choice" question: select the correct answer.
What is the interpretation of P(B|A) in the context of this study?

(D) and (E) are both interpretations of P(B|A).
Resposta Correta:
(D) and (E) are both interpretations of P(B|A).
Feedback da resposta: This is correct.

Pergunta 4
1 em 1 pontos

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)?

0≤P(A)≤1
Resposta Correta:
0≤P(A)≤1

Feedback da
resposta:
This is correct. The probability of an event can any number
between 0 and 1, including 0 and 1. In other words, the
probability of an event cannot be more than 1 or less than 0.

Pergunta 5
0 em 1 pontos

An epidemiological study investigated the prevalence of two contagious
diseases ( Disease 1 and Disease 2) in the U.S.
Let A be the event that an individual contracts Disease 1
Let B be the event that an individual contracts Disease 2
Understand the reasoning behind the concept of conditional probability,
calculate conditional probabilities and interpret them.
"multiple choice" question: select the correct answer.

Of the individuals who did not contract Disease 2, what proportion will not
contract Disease 1?

.78
Resposta Correta:
.78/.85

Pergunta 6
0 em 1 pontos

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.
20% of all the students at a large university are international students. Two random
samples of students are chosen; a random sample of n=64 students and a random
sample of n=400 students. In which of the two samples is it more likely that more
than 25% of the sampled students are international students?

Resposta

The sample of size n=400 since in there is more variability in the
proportion of international students in larger samples.

Resposta
Correta:

The sample of size n=64 since in there is more variability in the
proportion of international students in smaller samples.

Pergunta 7
1 em 1 pontos

An epidemiological study reported the following information about two contagious
diseases:
· There is 15% chance of contracting Disease I
· There is 20% chance of contracting Disease II
· There is 2% chance of contracting both diseases
Let A be the event that a randomly chosen person contracts Disease I
Let B be the event that a randomly chosen person contracts Disease II
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
What does the probability P(A or B) mean in this context?

Resposta

The probability of contracting at least one of the two
diseases
Resposta Correta:
The probability of contracting at least one of the two
diseases
Feedback da
resposta:
This is correct. P(A or B) is the probability of contracting
Disease I or Disease II or both. In other words, P(A or B) is the
probability of contracting at lease one of the two diseases.

Pergunta 8
1 em 1 pontos

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.

Let A be the event that a document will reach its destination on time using a
certain service. If P(A)=.98
this means that:

Resposta

The document will almost always reach its destination on
time
Resposta Correta:
The document will almost always reach its destination on
time
Feedback da resposta: This is correct.

Pergunta 9
1 em 1 pontos

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.
Is it safe to assume that the sampling distribution of pˆ is approximately normal for
random samples of size n=21?

No, since n*p is not greater than 10.
Resposta Correta:
No, since n*p is not greater than 10.
Feedback da resposta: This is correct.

• Pergunta 10
0 em 1 pontos

The probability table below summarizes the information that a large cable company

Where:
T is the event that a randomly chosen customer subscribes to TV service
I is the event that a randomly chosen customer subscribes to Internet service

Create a probability table to organize and summarize information and use it to
find probabilities
"multiple choice" question: select the correct answer.
What is the correct representation and probability of the event that a customer
subscribes only to TV service?