Janice is considering buying a new home. She wants to estimate the monthly utilities (heating and air conditioning). She figures that the utilities are dependent on the size (square footage) of the home. She collects data on 10 homes in the neighborhood and finds a linear model to give the relationship between the size of the home and the monthly utilities. The equation of the line is ŷ = –8.1 + 1.91x, where ŷ is the mean monthly cost in utilities and x is the square footage of the home. The residual plot is shown. Based on the residual plot, is the linear model appropriate?

No, there is no clear pattern in the residual plot.
Yes, there is no clear pattern in the residual plot.
No, there are no homes between 2,300 and 2,900 square feet.
Yes, half of the residuals are positive and half are negative.

In a study of the relationship between socio-economic class and unethical behavior, 129 university of california undergraduates at berkeley were asked to identify themselves as having low or high social-class by comparing themselves to others with the most (least) money, most (least) education, and most (least) respected jobs. they were also presented with a jar of individually wrapped candies and informed that the candies were for children in a nearby laboratory, but that they could take some if they wanted. after completing some unrelated tasks, participants reported the number of candies they had taken. it was found that those who were identiď¬ed as upper-class took more candy than others. in this study, identify: (a) the cases, (b) the variables and their types, (c) the main research question, (d) identify the population of interest and the sample in this study, and (e) comment on whether or not the results of the study can be generalized to the population, and if the ď¬ndings of the study can be used to establish causal relationships.