Avaliação Statistics 4

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Pergunta 1
1 em 1 pontos
	
	
	
	Skill: Carry out the ANOVA procedure or comparing more than two population means.
"multiple choice" question: select the correct answer. Consistent with the group numbering, let μ1, μ2, and μ3 the mean SAT-Math score of all students who study on their own, work with a tutor, and complete a prep-course, respectively.
Which of the following are the appropriate null and alternative hypotheses?
	
	
	
	
	Resposta Selecionada:
 
H0: μ1 = μ2 = μ3
Ha: Not all the μ’s are equal 
Resposta Correta:
 
H0: μ1 = μ2 = μ3
Ha: Not all the μ’s are equal 
Feedback da resposta:
This is correct.
	
	
	
Pergunta 2
1 em 1 pontos
	
	
	
	Skills: Carry out the hypothesis test for the population proportion and draw conclusions in context
Carry out the hypothesis test for the population mean and draw conclusions in context
"multiple choice" question: select the correct answer. Suppose that we would like to test:H0:μ=10Ha:μ≠10at the 5% significance level. In addition, suppose that based on the collected data the 95% confidence interval for μ is (8.4, 11.1). Which of the following is correct?
	
	
	
	
	Resposta Selecionada:
 
Since 10 falls inside the confidence interval we can reject H0.
Resposta Correta:
 
Since 10 falls inside the confidence interval we can reject H0.
Feedback da resposta:
This is correct. Since 10 falls inside the confidence interval, it is, based on the data, a plausible value for μ. We therefore cannot reject H0.
	
	
	
Pergunta 3
0 em 1 pontos
	
	
	
	Skill: Carry out the two-sample t-test for comparing two population means when appropriate and draw meaningful conclusions
"multiple choice" question: select the correct answer. 
When the two-sample t-test is carried out, the researchers find that the test statistic is t = 2.83 and P-value = 0.003 P-value = 0.003 tells us that it would be quite unlikely to get results like that observed in our study (or more extreme) assuming that:
	
	
	
	
	Resposta Selecionada:
 
There is a difference in effectiveness between the two methods.
Resposta Correta:
 
There is no difference in effectiveness between the two methods.
	
	
	
Pergunta 4
0 em 1 pontos
	
	
	
	Skill: Carry out the ANOVA procedure or comparing more than two population means.
"multiple choice" question: select the correct answer. Results of the analysis that was run on the SAT-Math data:
Which of the following is an appropriate conclusion based on the output?
	
	
	
	
	Resposta Selecionada:
 
We can reject H0 and conclude that the data provides strong evidence that the three SAT-math score means (representing the three study strategies) are not all equal.
Resposta Correta:
 
Both (A) and (B) are are appropriate conclusions.
	
	
	
Pergunta 5
0 em 1 pontos
	
	
	
	Skill: Carry out the paired t-test when appropriate and draw meaningful conclusions
"multiple choice" question: select the correct answer. The researchers analyze the data and obtain the following output:
Which of the following is an appropriate conclusion based on the output?
	
	
	
	
	Resposta Selecionada:
The data do not provided sufficient evidence to reject H0. Thus, the researcher can conclude that the depression scores of students in the San Francisco and Bay area are, on average, higher following the earthquake.
Resposta Correta:
The data provided sufficient evidence to reject H0. Thus, the researcher can conclude that the depression scores of students in the San Francisco and Bay area are, on average, higher following the earthquake.
	
	
	
Pergunta 6
0 em 1 pontos
	
	
	
	The Medical College Admission Test (MCAT) is an examination for prospective medical students.Suppose that based on data collected from a random sample of 100 MCAT takers, the 95% confidence interval for μ, the mean MCAT score, was calculated to be (497, 503).
Skill:
Determine point estimates in simple cases, and make the connection between the sampling distribution of a statistic, and its properties as a point estimator.
"multiple choice" question: select the correct answer.
Which of the following is true regarding the sample proportion ρˆ, as a point estimator for the population proportion p?
	
	
	
	
	Resposta Selecionada:
 
The possible values of the sample proportion are centered at the population proportion.
Resposta Correta:
 
All of the above are true.
	
	
	
Pergunta 7
0 em 1 pontos
	
	
	
	A large insurance company wanted to estimate μ, the mean claim size (in $) on an auto insurance policy. A random sample of 225 claims was chosen and it was found that the average claim size was $2875. From past experience the population standard deviation is assumed to be $1350.
Skill: Calculate interpret the confidence interval for the population mean , and recognize the effect of level of confidence and sample size on the precision of the interval estimation.
"multiple choice" question: select the correct answer. Which of the following is the 95% confidence interval for μ?
	
	
	
	
	Resposta Selecionada:
 
(2785, 2965)
Resposta Correta:
 
(2695, 3055)
	
	
	
Pergunta 8
1 em 1 pontos
	
	
	
	Skill: Perform inference for the linear relationship between two quantitative variables
"multiple choice" question: select the correct answer. The observed relationship in the scatterplot means that:
	
	
	
	
	Resposta Selecionada:
 
The more intelligent the child is (as measured by IQ) the lower the risk of delinquent behavior.
Resposta Correta:
 
The more intelligent the child is (as measured by IQ) the lower the risk of delinquent behavior.
	
	
	
Pergunta 9
0 em 1 pontos
	
	
	
	Skill: Carry out the two-sample t-test for comparing two population means when appropriate and draw meaningful conclusions
"multiple choice" question: select the correct answer. 
Consider a situation where we are testing:
H0: μ1 − μ2 = 0
Ha: μ1 − μ2 ≠ 0
and the data analysis provides the following results:
•   Test statistic: t=−3.44
•   95% confidence interval for μ1 − μ2: (−1.74, −0.46) 
Which of the following is correct regarding the P-value of the test?
	
	
	
	
	Resposta Selecionada:
 
The P-value must be smaller than 0.05 since the test statistic t=−3.44 falls outside of the 95% confidence interval for μ1 − μ2.
Resposta Correta:
 
The P-value must be smaller than 0.05 since 0 falls outside of the 95% confidence interval for μ1 − μ2.
	
	
	
Pergunta 10
1 em 1 pontos
	
	
	
	Skill: Carry out the hypothesis test for the population proportion and draw conclusions in context. "multiple choice" question: select the correct answer.
In 2015 60% of all U.S. adults supported same-sex marriage. We would like to test whether the proportion of all U.S. adults who support same-sex marriage has increased since then. In a recent poll, 20 U.S. adults were randomly chosen and 13 of them (65%) supported same-sex marriage.Can we safely use the z-test for p in this case?
Which of the following is correct?
	
	
	
	
	Resposta Selecionada:
 
It is not safe to use the z-test for p in this case since 20*(1-.60) is not large enough.
Resposta Correta:
 
It is not safe to use the z-test for p in this case since 20*(1-.60) is not large enough.
Feedback da resposta:
This is correct. It is not safe to use the z-test for p in this case since n(1-p0)=20(1-.60)=8 is not at least 10.