Estatística nivel 4 em inglês EaD FMU

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Teste Atividade - Statistics 4 
Iniciado 31/05/19 20:57 
Enviado 31/05/19 21:22 
Status Completada 
Resultado da tentativa 3 em 10 pontos 
Tempo decorrido 24 minutos 
Resultados exibidos Respostas enviadas, Respostas corretas, Comentários 
• Pergunta 1 
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: [Sem Resposta] 
Resposta Correta: 
There is no difference in effectiveness between the two methods. 
 
 
• Pergunta 2 
1 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: 
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 correct interpretation of this confidence interval? 
 
Resposta 
Selecionada: 
 
We are 95% confident that the mean MCAT score is covered by the 
interval (497, 503). 
Resposta Correta: 
We are 95% confident that the mean MCAT score is covered by the 
interval (497, 503). 
Feedback da resposta: This is correct. 
 
 
• Pergunta 3 
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. 
 
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. 
The p-value in this case is the probability of getting data like that observed or more extreme 
(i.e., getting an observed non-completion rate of 22% or lower) assuming that: 
Resposta Selecionada: 
the new course format did not reduce the non-completion rate. 
Resposta Correta: 
the new course format did not reduce the non-completion rate. 
Feedback da 
resposta: 
This is correct. The p-value is calculated assuming that the null hypothesis is 
true. In this case, therefore, the p-value is calculated assuming that the new 
course format did not reduce the non-completion rate. 
 
 
• Pergunta 4 
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: 
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? 
 
Resposta Selecionada: [Sem Resposta] 
Resposta Correta: 
(498, 502) 
 
 
• Pergunta 5 
0 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: 
 
 
Resposta Selecionada: [Sem Resposta] 
Resposta Correta: 
birth order and delinquent behavior are independent. 
 
 
• 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: [Sem Resposta] 
Resposta Correta: 
All of the above are true. 
 
 
• Pergunta 7 
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. 
A certain type of lightbulb is advertised to have mean lifetime of 750 hours.A consumer 
advocacy group would like to check this claims and test:H0: The mean lifetime is the advertised 
750 hoursHa: The mean lifetime is less than the advertised 750 hours.The advocacy group 
chooses at random 40 lightbulbs and records their lifetimes. Based on the data the group 
concludes that the mean lifetime is less than 750 hours and accuses the manufacturer of the 
lightbulbs in false advertising. What type of error is possible in this situation? 
 
Resposta Selecionada: 
Type I 
Resposta Correta: 
Type I 
Feedback da 
resposta: 
This is correct. It is possible that the data provide evidence that the mean 
lifetime is less than advertised, when in reality it actually isn’t. In other words, 
in this situation there is a risk that the consumer advocacy group rejects the null 
hypothesis by mistake. This is type I error. 
 
 
• Pergunta 8 
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). 
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: [Sem Resposta] 
Resposta Correta: 
3 
 
 
• Pergunta 9 
0 em 1 pontos 
 
Skill: Carry out the hypothesis test for the population proportion and draw conclusions in 
context. "multiplechoice" 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: 
 [Sem Resposta] 
Resposta Correta: 
It is not safe to use the z-test for p in this case since 20*(1-.60) is not 
large enough. 
 
 
• Pergunta 10 
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. 
If the insurance company wanted to estimate μ with 99% confidence interval with a margin of 
error of 180, how large a sample of claims would they have needed? 
Resposta Selecionada: [Sem Resposta] 
Resposta Correta: 
374 
 
 
Sexta-feira, 31 de Maio de 2019 21h22min14s BRT