Statistics_3

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Pergunta 1
1 em 1 pontos
	
	
	
	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.
Four U.S. adults are selected at random. What is the probability that none of four belongs to the Upper Class?
	
	
	
	
		Resposta Selecionada:
	 
.79 4 
	Resposta Correta:
	 
.79 4 
	Feedback da resposta:
	This is correct.
P(None of the four belongs to Upper class) = P(1stnot Upper and 2nd not Upper and 3rd not Upper and 4th not Upper) = = [independence] = (1 -- .21)4 = .794
	
	
	
Pergunta 2
1 em 1 pontos
	
	
	
	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.
What is the probability that a randomly chosen U.S. adults belongs to the Middle or Upper class?
	
	
	
	
		Resposta Selecionada:
	 
.71
	Resposta Correta:
	 
.71
	Feedback da resposta:
	This is correct. Since the events “belongs to Middle Class” and “belongs to Upper Class” are disjoint, P(Middle or Upper)=P(Middle)+P(Upper)=.50+.21=.71
	
	
	
Pergunta 3
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?
	
	
	
	
		Resposta Selecionada:
	 
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 4
0 em 1 pontos
	
	
	
	A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
"multiple choice" question: select the correct answer.
Given that the patient survives, what is the probability that a suitable transplant was found (what is P(T|S))? (Some answers were rounded).
	
	
	
	
		Resposta Selecionada:
	 
.75
	Resposta Correta:
	 
.616
	
	
	
Pergunta 5
1 em 1 pontos
	
	
	
	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.
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?
	
	
	
	
		Resposta Selecionada:
	 
Y has a binomial distribution with n=20 and p=.18
	Resposta Correta:
	 
Y has a binomial distribution with n=20 and p=.18
	Feedback da resposta:
	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 6
0 em 1 pontos
	
	
	
	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.
Find the probability of events in the case when all outcomes are equally likely.
"multiple choice" question: select the correct answer.
Assume that each time that the family goes out to eat they choose one of the three restaurants at random, and again, let A be the event that on a given the family eats in R2 exactly once. What is P(A)?
	
	
	
	
		Resposta Selecionada:
	 
1/9
	Resposta Correta:
	 
4/9
	
	
	
Pergunta 7
1 em 1 pontos
	
	
	
	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?
	
	
	
	
		Resposta Selecionada:
	 
0.16
	Resposta Correta:
	 
0.16
	Feedback da resposta:
	This is correct. By the Standard Deviation Rule, there is 68% chance that a randomly chosen U.S. adults sleeps between 7.5-1.2=6.3 hours and 7.5+1.2=8.7 hours.
Therefore P(X > 8.7) = (1- .68)/2 = 0.16
	
	
	
Pergunta 8
0 em 1 pontos
	
	
	
	A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is not found and the patient survives?
	
	
	
	
		Resposta Selecionada:
	 
.56
	Resposta Correta:
	 
.14
	
	
	
Pergunta 9
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 Selecionada:
	 
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 10
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.
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 Selecionada:
	 
The sample of size n=64 since in there is more variability in the proportion of international students in smaller samples.
	Resposta Correta:
	 
The sample of size n=64 since in there is more variability in the proportionof international students in smaller samples.
	Feedback da resposta:
	This is correct.