Atividade - statistics 3

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Pergunta 1
1 em 1 pontos
	
	
	
	A large cable company provides the following information regarding its customers:
· 50% of all customers subscribe to internet service.
· If a customer is an internet subscriber, there is 64% chance that he/she is also a phone subscriber.
· If a customer is a phone subscriber, there is 80% chance that he/she is also an internet subscriber.
Let A be the event that a customer subscribes to internet service
Let B be the event that a customer subscribes to phone service
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a customer subscribes to both internet and phone service?
	
	
	
	
		Resposta Selecionada:
	 
P(A) * P(B|A) = .50 * .64 = .32
	Resposta Correta:
	 
P(A) * P(B|A) = .50 * .64 = .32
	Feedback da resposta:
	This is correct. P(A and B) = P(A) * P(B|A) = .50 * .64 = .32
	
	
	
Pergunta 2
1 em 1 pontos
	
	
	
	A large cable company provides the following information regarding its customers:
· 50% of all customers subscribe to internet service.
· If a customer is an internet subscriber, there is 64% chance that he/she is also a phone subscriber.
· If a customer is a phone subscriber, there is 80% chance that he/she is also an internet subscriber.
Let A be the event that a customer subscribes to internet service
Let B be the event that a customer subscribes to phone service
Determine whether two events are independent
"multiple choice" question: select the correct answer.
Are the two subscriptions (phone, Internet) independent of each other?
	
	
	
	
		Resposta Selecionada:
	 
No, since P(A)=.50 is not equal to P(A|B) = .80
	Resposta Correta:
	 
No, since P(A)=.50 is not equal to P(A|B) = .80
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 3
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 price of a European tour includes stopovers at five cities to be selected from 15 cities. In how many ways can a traveler plan such a tour if the traveler can only choose the five cities (the order is determined by the travel company).
	
	
	
	
		Resposta Selecionada:
	 
3,003
	Resposta Correta:
	 
3,003
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 4
1 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.
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?
	
	
	
	
		Resposta Selecionada:
	 
S= { (R1, R1) (R2, R2) (R3, R3) (R1, R2) (R2, R1) (R1, R3) (R3, R1) (R2, R3) (R3, R2) }
	Resposta Correta:
	 
S= { (R1, R1) (R2, R2) (R3, R3) (R1, R2) (R2, R1) (R1, R3) (R3, R1) (R2, R3) (R3, R2) }
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 5
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
Determine whether two events are independent
"multiple choice" question: select the correct answer.
Recall that the epidemiological study reported the following:
· There is 15% chance of contracting Disease 1 (Event A)
· There is 10% chance of contracting Disease 2 (Event B)
· There is 3% chance of contracting both Disease 1 and Disease 2
Are the two diseases being contracted independently of each other (are events A, B independent)?
	
	
	
	
		Resposta Selecionada:
	 
No, since P(A and B)=.03 is not equal to P(A)*P(B)=.15*.10=.015
	Resposta Correta:
	 
No, since P(A and B)=.03 is not equal to P(A)*P(B)=.15*.10=.015
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 6
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.
What is the probability that the patient survives? (what is P(S)?)
	
	
	
	
		Resposta Selecionada:
	 
.225
	Resposta Correta:
	 
.365
	
	
	
Pergunta 7
1 em 1 pontos
	
	
	
	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?
	
	
	
	
		Resposta Selecionada:
	
2000 randomly chosen individuals from this population are tested and 102 of them are found to carry the HIV virus.
	Resposta Correta:
	
2000 randomly chosen individuals from this population are tested and 102 of them are found to carry the HIV virus.
	Feedback da resposta:
	This is correct.
	
	
	
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 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 9
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.
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.
	
	
	
	
		Resposta Selecionada:
	 
.50 * .29
	Resposta Correta:
	 
.50 * .29
	Feedback da resposta:
	This is correct. P(A and B) = [A, B independent] = P(A) * P(B) = .50 * .29
	
	
	
Pergunta 10
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, calculateconditional 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?
	
	
	
	
		Resposta Selecionada:
	 
.78/.85
	Resposta Correta:
	 
.78/.85
	Feedback da resposta:
	This is correct. P(Not B | Not A)=P(Not A and Not B)/P(Not A)=.78/.85