statistic 03

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· Pergunta 1
1 em 1 pontos
	
	
	
	The National Survey on Drug and Health reported that 15% females in the age group of 12 to 20 years old are binge drinkers.
A random sample of 10 females from this age group is chosen, and let the random variable X be the number of females (out of 10) who are binge drinkers.
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
Which of the following is the correct probability distribution function of X?
	
	
	
	
		Resposta Selecionada:
	 
P(X=x)=10!x!(10−x)! ⋅ 0.15x ⋅ 0.8510−x x=0, 1, 2, 3...9, 10
	Resposta Correta:
	 
P(X=x)=10!x!(10−x)! ⋅ 0.15x ⋅ 0.8510−x x=0, 1, 2, 3...9, 10
	Feedback da resposta:
	This is correct.
	
	
	
· Pergunta 2
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. 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?
	
	
	
	
		Resposta Selecionada:
	 
0.2
	Resposta Correta:
	 
3
	
	
	
· 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.
What are the mean and standard deviation of X, the number of females out of the 10 chosen who are binge drinkers?
	
	
	
	
		Resposta Selecionada:
	 
μx=10(0.15) , σx=10(0.15)(0.85)−−−−−−−−−−−−√
	Resposta Correta:
	 
μx=10(0.15) , σx=10(0.15)(0.85)−−−−−−−−−−−−√
	Feedback da resposta:
	This is correct.
	
	
	
· Pergunta 4
0 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. What is the probability that both adults belong to the same social class?
	
	
	
	
		Resposta Selecionada:
	 
2*(.29 * .50 * 21)
	Resposta Correta:
	 
.29 * .29 + .50 * .50 + .21 * .21
	
	
	
· Pergunta 5
1 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
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?
	
	
	
	
		Resposta Selecionada:
	 
.0401
	Resposta Correta:
	 
.0401
	Feedback da resposta:
	This is correct.
P(X>6200)=[z=6200−5500400=1.75]=P(Z>1.75)=[table]=1−.9599=0401
	
	
	
· Pergunta 6
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
"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
	
	
	
	
		Resposta Selecionada:
	 
Independent
	Resposta Correta:
	 
Independent
	Feedback da resposta:
	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 7
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.
The study reported the following:
· There is 15% chance of contracting Disease 1
· There is 10% chance of contracting Disease 2
· There is 3% chance of contracting both Disease 1 and Disease 2
Which of the following is true regarding P(B|A)?
	
	
	
	
		Resposta Selecionada:
	 
P(B|A) = .20
	Resposta Correta:
	 
P(B|A) = .20
	Feedback da resposta:
	This is correct.
	
	
	
· Pergunta 8
1 em 1 pontos
	
	
	
	The mammogram is the most common screening test for breast cancer. Its purpose is to detect breast cancer early when it is easier to treat.
A positive mammogram test results indicates that signs of possible cancer were found.
A negative mammogram test rests indicates that no signs of cancer were found.
Like any other medical test, the mammogram test is not “perfect”.
The following information is available:
· 1% of women over 50 have breast cancer.
· Given that a woman over 50 has breast cancer, there 90% chance that the mammogram test will be positive (i.e., detect the cancer)
· Given that a woman over 50 does not have cancer, there is 8% chance that the mammogram test will be positive (by mistake).
Let C be the event that a woman over 50 has breast cancer
Let M be the event that the mammogram test will be positive.
Understand the reasoning behind the concept of conditional probability, calculate conditional probabilities and interpret them.
"multiple choice" question: select the correct answer.
The problem gives you three pieces of information (probabilities). Which of the following probabilities is not given in the problem?
	
	
	
	
		Resposta Selecionada:
	 
P(C and M)
	Resposta Correta:
	 
P(C and M)
	Feedback da resposta:
	This is correct.
	
	
	
· Pergunta 9
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 found and the patient survives?
	
	
	
	
		Resposta Selecionada:
	 
.14
	Resposta Correta:
	 
.225
	
	
	
· Pergunta 10
0 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:
	 
2*(.50 + .29)
	Resposta Correta:
	 
.50 * .29