Atividade - Statistics 3

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Pergunta 1
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 proportion of international students in smaller samples.
	Feedback da resposta:
	This is correct.
	
	
	
Pergunta 2
0 em 1 pontos
	
	
	
	The probability table below summarizes the information that a large cable company provides about its customers:
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 probability that a randomly chosen customer subscribes to exactly one of the two services?
	
	
	
	
		Resposta Selecionada:
	 
.05
	Resposta Correta:
	 
.15
	
	
	
Pergunta 3
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
"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:
	 
Not independent
	Resposta Correta:
	 
Independent
	
	
	
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.
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*.50 + .29*.29
	Resposta Correta:
	 
.50 * .29
	
	
	
Pergunta 5
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.
Understand how a density function is used to find probabilities involving continuous random variables.
"multiple choice" question: select the correct answer.
The shaded area in the image below represents which of the following probabilities?
	
	
	
	
		Resposta Selecionada:
	 
P(8.5<X≤9.5)
	Resposta Correta:
	 
P(8.5<X≤9.5)
	Feedback da resposta:
	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
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:
	 
.225
	Resposta Correta:
	 
.14
	
	
	
Pergunta 7
0 em 1 pontos
	
	
	
	Based on the Journal of the American Medical Association, weights of all newborn babies in U.S. follow a normal distribution with a mean of 3420 grams and standard deviation of 500 grams. The weights of 625 randomly selected newborns were recorded and it was found that the average and standard deviation in this sample were 3450 grams and 490, respectively.
Skill: Distinguish between a parameter and a statistic and recognize the concept of sampling variability.
"multiple choice" question: select the correct answer.
Which of the following is a statistic?
	
	
	
	
		Resposta Selecionada:
	 
Both 3450 and 490 are statistics.
	Resposta Correta:
	 
3420
	
	
	
Pergunta 8
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
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
How much should be budgeted for weekly maintenance and repair so that there is only 1.5% chance that the cost will exceed the budgeted amount.
	
	
	
	
		Resposta Selecionada:
	 
5702.4
	Resposta Correta:
	 
6368
	
	
	
Pergunta 9
0 em 1 pontos
	
	
	
	Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
	
	
	
	
		Resposta Selecionada:
	 
0.46
	Resposta Correta:
	 
0.74
	
	
	
Pergunta 10
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.
Apply probability rules in order to find the likelihood of 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:
	
	
	
	
		Resposta Selecionada:
	 
in a given month, the family eats at R1 at most once
	Resposta Correta:
	 
in a given month, the family eats at R1 twice