The PDF linked below challenges a student to demonstrate understanding of the concepts of scatter plots. Not only must a student be able to identify specific information in a scatter plot, a student must be able to describe the main features of a scatter plot and make sense of trends in the scatter plot in order to graph a line to represent average density and calculate density relationships in the context of this particular situation.
http://www.insidemathematics.org/common-core-math-tasks/high-school/HS-S-2004%20Population.pdf