Blog

Which of the following measures of center and spread are most appropriate for describing a symmetric bell-shaped distribution?

Researchers took 60 people, 45 of whom had never smoked, and divided them into two groups:  those with low exposure to second hand smoke and those with high exposure to second hand smoke. They took MRI images of the lungs of both groups of subjects, and found that the lungs of those who had high exposure to second hand smoke had many tiny holes and spaces inside their lungs that should not be there. This study is an example of

Marine biologists have determined that a certain species of whale has overall lengths that are Normally distributed with mean 60 feet and standard deviation 12 feet.   A research vessel spots a whale of this species and estimates its length to be 47 feet. What is the z-score of this length? (Round your answer to 2 decimal places.)

An experiment exposed mice to varying light conditions at night. The scatterplot of Body Mass Gain versus Percent of Calories showed evidence of a linear relationship. The resulting least squares regression line equation  Body Mass Gain = 1.622 + 0.115 x Percent of Calories has an R2 value of 0.08. Which of the following is the slope of the least squares regression line equation?

The Central Limit Theorem applies to

An experiment investigated whether cell phone use increases drivers’ reaction times.  College students were randomly allocated to a cell phone group or a control group.  The experiment measures subjects’ response times (in milliseconds) in a driving simulation.  For the cell phone group, the sample mean time was 585.2, the sample standard deviation was 89.6, and the sample size was 32.  For the control group, the sample mean time was 533.7, the sample standard deviation was 65.3, and the sample size was 32. The null hypothesis is that the mean reaction times are equal. Which is the appropriate alternative hypothesis for this investigation?

A researcher conducted a study to investigate the performance of students on an exam and their levels of anxiety.  An anxiety survey is given to students before the exam.  A higher score on the survey means the student experiences a higher level of anxiety.  The researcher claims that the correlation of -0.91 shows there is a strong causal relationship between anxiety and exam performance.  Explain what is wrong with this interpretation.

A researcher conducted a study to investigate the performance of students on an exam and their levels of anxiety.  An anxiety survey is given to students before the exam.  A higher score on the survey means the student experiences a higher level of anxiety.  The researcher claims that the correlation of -0.91 shows there is a strong causal relationship between anxiety and exam performance.  Explain what is wrong with this interpretation.

An experiment investigated whether cell phone use changes drivers’ reaction times.  College students were randomly allocated to a cell phone group or a control group.  The experiment measures subjects’ response times (in milliseconds) in a driving simulation.  Data were collected for both groups and the p-value for the appropriate hypothesis test was calculated to be 0.06.  Which of the following statements is correct?

A seller, who sells pet products within the United States, on Amazon wants to survey customer satisfaction.  Match the sampling design with the appropriate description.