Estatistic 4

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Pergunta 1
Resposta Selecionada: 
Resposta Correta: 
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?
It is safe to use the z-test for p in this case.
It is not safe to use the z-test for p in this case since 20*(1-.60) is not large enough.
Pergunta 2
Resposta Selecionada: 
Resposta Correta: 
Skill: Perform inference for the linear relationship between two quantitative variables
"multiple choice" question: select the correct answer. Since the data displayed a linear relationship, the correlation
coefficient was calculated and was found to be r=−0.81. Based on the scatterplot and the value of the correlation
coefficient, it would make sense to test the significance of this observed linear relationship between IQ and DI. The
appropriate hypotheses are: 
Ha: IQ and DI are linearly related.
H0: IQ and DI are not linearly relatedHa: IQ and DI are linearly related.
Pergunta 3
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:
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Resposta
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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?
 The P-value must be larger than 0.05 since 0 falls outside of the 95% confidence interval for
μ1 − μ2.
The P-value must be smaller than 0.05 since 0 falls outside of the 95% confidence interval
for μ1 − μ2.
Pergunta 4
In 1989, a major earthquake struck the San Francisco Bay area. The earthquake caused major damage, and would
be expected to have emotional post-traumatic stress effects on the residents. Any psychological measure taken in
the days or weeks just before the quake would have provided a good baseline for subsequent comparison.Two
Stanford researchers happened to measure the depression level of 25 college students from the San Francisco Bay
area two weeks before the quake. They then measured depression for the same group of 25 students again 10 days
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after the earthquake to track the students’ adjustment to the traumatic event. The depression scale that the
researchers used is such that the higher the score the more depressed the individual is. Do the data provide
evidence that students in the San Francisco Bay area became more depressed following the earthquake?
Let [Math Processing Error] be the mean difference in depression score (Before earthquake – After earthquake) of
all students in the San Francisco Bay area.
Skill: Carry out the paired t-test when appropriate and draw meaningful conclusions
"multiple choice" question: select the correct answer. Which of the following are the appropriate null and alternative
hypotheses?
H0: μd = 0
Ha: μd ≠ 0
H0: μd = 0
Ha: μd < 0
Pergunta 5
Resposta Selecionada: 
Resposta Correta: 
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:
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. If we were to use the same data to calculate a 90% confidence
interval for μ, the mean MCAT score, which of the following could be this interval?
(496, 504)
(498, 502)
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Pergunta 6
Resposta Selecionada: 
Resposta Correta: 
A random sample of 700 U.S. adults was asked the following question:Do you approve or disapprove of the way
Donald Trump is handling his job as president?280 of the 700 responded that they approve. 
Skill: Calculate interpret the confidence interval for the population proportion p, 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 correct 90% confidence interval
for p, the proportion of all U.S. adults who approve of the way Donald Trump is handling his job as president?
(Answers are rounded to two decimal places).
(0.36, 0.44) 
(0.37, 0.43) 
Pergunta 7
Resposta Selecionada: 
Resposta Correta: 
t was found that 25% of community college students in the state of California do not complete their Intro Stats class
(i.e., either withdraw mid-course or fail). In an effort to reduce the non-completion rate, a new hybrid course format
(on-line materials + face-to-face instructions) was designed to replace the traditional course. To test its effectiveness,
a random sample of 300 California community college students who took the Intro Stats course in the new format
was chosen and it was found that 66 of them (22%) did not complete the course.Do these data provide enough
evidence to conclude that when the course is taught in the new format the non-completion rate is reduced? Let p be
the proportion of all community college students in the state of California who took Intro Stats in the new format and
did not complete the course.
Skill: Carry out the hypothesis test for the population proportion and draw conclusions in context
"multiple choice" question: select the correct answer. Which of the following are the correct null and alternative
hypotheses in this case? 
H0: p=0.22 ; Ha: p<0.22
H0: p=0.25 ; Ha: p≠0.25
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Pergunta 8
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Resposta
Correta:
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. 
The data analysis also found that the 95% confidence interval for μ1 − μ2 is (1.1, 6.1).Which of the following is the
correct interpretation of this interval? 
There is 95% chance that if a child is taught by Method 2, his/her performance score will be
between 1.1 and 6.1. 
We are 95% confident that the mean performance score of all children taught by Method 1 is
between 1.1 and 6.1 points higher than the mean performance score of all children taught by
Method 2.
Pergunta 9
Resposta
Selecionada:
Resposta
Correta:
A recent Gallup poll concerning abortion reported that 30% (.30) of the sampled U.S. adults said that abortion should
be legal in all cases. The report added that the margin of error at the 95% confidence level was 4% (.04).
Skill: Calculate interpret the confidence interval for the population proportion p, 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 correct interpretation of the margin
of error in this case? 
We are 95% confident that the proportion of all U.S. adults who feel that abortion should be legal
in all cases is more than .04 away from .30. 
 We are 95% confident that the proportion of all U.S. adults who feel that abortion should be legal
in all cases is no more than .04 away from .30. 
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Pergunta 10
Resposta
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Resposta
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Skill: Recognize the different steps of hypothesis testing and its logic. In particular, determinethe hypotheses,
interpret the p-value and draw conclusions.
"multiple choice" question: select the correct answer. Suppose that the p-value of a test is 0.035. Which of the
following is correct regarding the conclusions we can draw?
We can reject the null hypothesis at a significance level of 0.01 but cannot reject the null
hypothesis at a significance level of 0.05
We can reject the null hypothesis at a significance level of 0.05 but cannot reject the null
hypothesis at a significance level of 0.01
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