## Exam (elaborations)

# MATH 225N Week 8 Interpret the Slope & Y-Intercept of the Least Squares Regression Line

MATH 225N Week 8 Interpret the Slope & Y-Intercept of the Least Squares Regression Line (Q & A) Question: A scientific study on gerbil population growth results in the data below….. The least squares regression line modeling this data is given by yˆ=13.3 5.567x. What is the intercept of the regression line? Round your answer to one decimal place. Question: True or False: The more mangoes you eat, the more rashes you get. Question: Suppose that a large controlled experiment tests whether caffeine improves reaction times. A very large number of randomly selected participants are randomly given identical-seeming pills with varying doses of caffeine (including none) and then given tests of reaction times under the same conditions. The experiment finds a strong negative correlation between caffeine dose and reaction time. (Note that lower reaction times are better.)…. Identify what can … concluded based on this information. Question: True or false: The larger the truck, the larger the load it can fit. Question: An observational study shows a moderate negative correlation between the price of the car a person owns and the happiness of that person. Answer the following question based only on this information….. True or false: It can … concluded that in general, owning a more expensive car makes people less happy. Question: True or False: The larger the number of cavities, the older the person. Question: True or false: Increases in height cause increases in shoe size. Question: Suppose that data collected from police reports of motor vehicle crashes show a moderate positive correlation between the speed of the motor vehicle at the time of the crash and the severity of injuries to the driver. Answer the following question based only on this information… True or false: It can … concluded that the faster a motor vehicle is traveling at the time of a crash, the more severe the injuries to the driver are. Question: A plot of time versus the price of a best-selling model of television has horizontal units of years since 2000and vertical units of dollars. The best fit line of the data are … by the equation y=−75x 550, where x=year and y= Question: Which of the following data sets or plots could have a regression line with a negative y-intercept? Select all that apply. Question: The scatter plot below shows the average cost of a designer jacket in a sample of years between 2000and 2015. The least squares regression line modeling this data is given by yˆ=−4815 765x. Question: George is an avid plant lover and is concerned about the lack of daffodils that grow in his backyard. He finds the growth of the daffodils, G, is dependent on the percent of aluminum measured in the soil, x, and can be modeled by the function…. G(x)=16−4x….. Draw the graph of the growth function by plotting its G-intercept and another point. Question: What percent of aluminum in the soil must there be for the daffodils to grow only by 5centimeters? …. Round your final answer to the nearest whole number. Question: True or False: The longer a road, the greater the amount of time it will take to travel its length. Question: True or False: The more time it takes to travel a road, the longer the road is. Question: True or false: Increases in height cause increases in shoe size. Question: A large observational study asks participants about caffeine consumption and sleep duration. The study finds that people with the largest caffeine intake have the shortest sleep duration…. Identify the relation between caffeine consumption and sleep duration. Y-Intercept