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Tree diameters are related to “growth rings” in trees and larger diameters are associated with taller trees. The scatter plot of a survey of 958 trees in an old-growth forest in Canada showed evidence of a linear relation between tree height (m) and diameter (cm).   The resulting least squares regression line equation  Height = 2.79 + 0.55× Diameter has an R2 value of 0.92. Which of the following is the slope of the least squares regression line equation?

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.  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?

Alcohol was a factor in about 10% of all automobile crashes in Ohio during 2016, but driver inebriation was present in almost 28% of crashes in which a fatality occurred. Here is some data on fatal vehicle accidents by season:        ALCOHOL INVOLVED NO ALCOHOL TOTAL WINTER 60 158 218 SPRING 73 172 245 SUMMER 110 243 353 FALL 70 247 317 TOTAL 313 820 1133 a.  What is the probability that a fatal vehicle accident in Ohio will occur in the winter?  Report your answer to 3 decimal places. [A] b. What is the probability that a fatal vehicle accident in Ohio both occurs in winter and alcohol is involved? Report your answer to 3 decimal places. [B] c.  Given the fatal vehicle accident happened in the winter, what is the conditional probability that alcohol is involved? Report to 3 decimal places. [C] d.  What is the relative risk of an alcohol-involved fatal vehicle accident in Ohio in summer compared to winter? Report to 3 decimal places.  [D]  

Researchers took 100 people who had tested positive for COVID-19, 20 of whom had diabetes, and divided them into two groups: those with low levels of Vitamin D and those with normal levels of Vitamin D.  They looked at their medical records and found that those who had low levels of Vitamin D had a higher likelihood of severe COVID-19 symptoms. This is an example of

A researcher conducted a study to investigate college safety.  He found that the more students a college has, the higher the crime rate in the surrounding area. The researcher claims that the correlation of 0.91 shows there is a strong causal relationship between the number of students and crime rates.  Explain what is wrong with this interpretation.

Which of the following graphs is appropriate to display one categorical variable?

Alcohol was a factor in about 10% of all automobile crashes in Ohio during 2016, but driver inebriation was present in almost 28% of crashes in which a fatality occurred. Here is some data on fatal vehicle accidents by season:        ALCOHOL INVOLVED NO ALCOHOL TOTAL WINTER 60 158 218 SPRING 73 172 245 SUMMER 110 243 353 FALL 70 247 317 TOTAL 313 820 1133 a.  What is the probability that a fatal vehicle accident in Ohio will occur in the winter?  Report your answer to 3 decimal places. [A] b. What is the probability that a fatal vehicle accident in Ohio both occurs in winter and alcohol is involved? Report your answer to 3 decimal places. [B] c.  Given the fatal vehicle accident happened in the winter, what is the conditional probability that alcohol is involved? Report to 3 decimal places. [C] d.  What is the relative risk of an alcohol-involved fatal vehicle accident in Ohio in summer compared to winter? Report to 3 decimal places.  [D]  

Which of the following is not true about the binomial distribution?

Which of the following is not true about the binomial 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