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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. 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: 3 Resposta Correta: 3 Feedback da resposta: This is correct. Z=x¯ −μσn√=5.1−3.67.5225√=1.50.5=3 Pergunta 2 1 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: .15 Resposta Correta: .15 Feedback da resposta: This is correct. 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 "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: .50 Resposta Correta: .71 Pergunta 4 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 Selecionada: 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 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 Understand the reasoning behind the concept of conditional probability, calculate conditional probabilities and interpret them. "multiple choice" question: select the correct answer. Below is the probability table for the two contagious diseases example. A is the event that an individual contracts Disease 1 B is the event that an individual contracts Disease 2 The fraction .12/.90 represents: Resposta Selecionada: P(A | Not B) Resposta Correta: P(A | Not B) Feedback da resposta: This is correct. P(A | Not B)=P(A and Not B)/P(Not B)=.12/.90 Pergunta 6 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 7 1 em 1 pontos 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 statements is consistent with the idea of sampling variability? Resposta Selecionada: If we were to select a different random sample of 625 newborns, we can expect the mean and standard deviation in this sample to be different than the mean and the standard deviation in the first sample. Resposta Correta: If we were to select a different random sample of 625 newborns, we can expect the mean and standard deviation in this sample to be different than the mean and the standard deviation in the first sample. Feedback da resposta: This is correct. The idea of sampling variability is that no two random samples from the same population are identical. In other words, random samples vary. Pergunta 8 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 9 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. In context, the fact that P(Not T and Not I) = 0 means that: Resposta Selecionada: All the customers subscribe to both services. Resposta Correta: All the customers subscribe to at least one of the two services. 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, 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? Resposta Selecionada: (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.
