Statistics 4

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Curso Estatística 
Teste Atividade - Statistics 4 
Iniciado 16/07/20 23:55 
Enviado 17/07/20 00:32 
Status Completada 
Resultado da 
tentativa 
9 em 10 pontos 
Tempo decorrido 36 minutos 
Resultados exibidos Respostas enviadas, Respostas corretas, 
Comentários 
 Pergunta 1 
1 em 1 pontos 
 
Skill: Determine the likelihood of making type I and type II errors, and 
explain how to reduce them, in context. 
"multiple choice" question: select the correct answer. What can be 
done in order to reduce the risk of Type I error? 
 
Resposta 
Selecionada: 
 
Choose a smaller significance level (for 
example, 0.01 instead of 0.05) 
Resposta Correta: 
Choose a smaller significance level (for 
example, 0.01 instead of 0.05) 
Feedback da resposta: This is correct. 
 
 
 Pergunta 2 
1 em 1 pontos 
 
Skill: Perform inference for the linear relationship between two 
quantitative variables 
"multiple choice" question: select the correct answer. The following 
output is available: 
 
Based on the output, which of the following is the appropriate 
conclusion? 
 
Resposta 
Selecionada: 
 
The data provide strong evidence that IQ and DI 
are linearly related. 
Resposta Correta: 
The data provide strong evidence that IQ and DI 
are linearly related. 
Feedback da resposta: This is correct. 
 
 
 Pergunta 3 
1 em 1 pontos 
 
Skill: Carry out the hypothesis test for the population mean and draw 
conclusions in context 
"multiple choice" question: select the correct answer. Which of the 
following is true regarding the t-distribution. 
 
Resposta Selecionada: 
All of the above are correct. 
Resposta Correta: 
All of the above are correct. 
Feedback da resposta: This is correct. 
 
 
 Pergunta 4 
1 em 1 pontos 
 
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). 
 
Resposta Selecionada: 
(0.37, 0.43) 
Resposta Correta: 
(0.37, 0.43) 
 
Feedba
ck da 
respost
a: 
This is correct. 
ρˆ±1.645⋅ρˆ(1−ρˆn−−−−−√=.40±1.645⋅.40(.60)700−−−−−√≈.4
0±.03=(.37, .43) 
 
 Pergunta 5 
1 em 1 pontos 
 
It 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. 
The p-value is this case is above 10%. Which of the following is the 
appropriate conclusion at the 5% significance level? 
 
Resposta 
Selecionada: 
 
We cannot reject H0. The data do not provide 
enough evidence to conclude that the new course 
format reduces the non-completion rate. 
Resposta 
Correta: 
 
We cannot reject H0. The data do not provide 
enough evidence to conclude that the new course 
format reduces the non-completion rate. 
Feedback da 
resposta: 
This is correct. Since p-value > 5%, we cannot 
reject H0. 
 
 
 Pergunta 6 
0 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 
cannot reject H0. 
Resposta Correta: 
Since 10 falls inside the confidence interval we 
can reject H0. 
 
 
 Pergunta 7 
1 em 1 pontos 
 
The question whether birth order affects juvenile delinquency was 
examined in a large study using a high school population. A random 
sample of 1,060 boys attending public school were given a 
questionnaire that measured delinquent behavior and then classified 
each boy as either 'Yes' or 'No'. Each boy also indicated his birth order: 
the oldest, in between, or the youngest. The results are summarized in 
the following two-way table: 
 
To test whether the data provides significant evidence for a relationship 
between birth order and delinquent behavior, we will use the Chi-square 
test for independence. 
Skill: Carry out the chi-square test for the independence of two 
categorical variables and draw meaningful conclusions. 
 
"multiple choice" question: select the correct answer. Two-way table that 
summarizes the results of the study: 
Resposta Selecionada: 
19.8 
Resposta Correta: 
19.8 
Feedback da 
resposta: 
This is correct. The expected count of children who are 
the youngest child and delinquent is: (row total * column 
total)/table total = 241*87/1060=19.8. 
 
 
 Pergunta 8 
1 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. 
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 the point estimate for μ? 
 
Resposta Selecionada: 
$2875 
Resposta Correta: 
$2875 
Feedback da 
resposta: 
This is correct. The point estimate for the 
population mean is the sample mean. 
 
 
 Pergunta 9 
1 em 1 pontos 
 
Skill: Recognize the different steps of hypothesis testing and its logic. 
In particular, determine the 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? 
 
Resposta 
Selecionada: 
 
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 
Resposta 
Correta: 
 
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 
Feedback 
da 
resposta: 
This is correct. We can reject the null hypothesis when 
the p-value is smaller than the significance level. 
Therefore, if p-value=0.035, 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. 
 
 
 Pergunta 10 
1 em 1 pontos 
 
The Medical College Admission Test (MCAT) is an examination for 
prospective medical students.Suppose thatbased 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). 
Skills: 
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. 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. 
What is the margin of error of this confidence interval? 
 
Resposta Selecionada: 
3 
Resposta Correta: 
3 
Feedback da 
resposta: 
This is correct. The margin of error is half the width 
of the confidence interval which in this case is (503-
497)/2=3. 
 
 
Sexta-feira, 31 de Julho de 2020 21h16min18s BRT 
 
	 Pergunta 1
	 Pergunta 2
	 Pergunta 3
	 Pergunta 4
	 Pergunta 5
	 Pergunta 6
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	 Pergunta 10