DATA EXPLORATION
Mr. Starnes teaches AP® Statistics, but he also does the class scheduling for the high school. There are two
AP® Statistics classes—one taught by Mr. Starnes and one taught by Ms. McGrail. The two teachers give the same first
test to their classes and grade the test together. Mr. Starnes’s students earned an average score that was 8 points higher
than the average for Ms. McGrail’s class. Ms. McGrail wonders whether Mr. Starnes might have “adjusted” the class
rosters from the computer scheduling program. In other words, she thinks he might have “stacked” his class. He denies
this, of course. To help resolve the dispute, the teachers collect data on the cumulative grade point averages and SAT
Math scores of their students. Mr. Starnes provides the GPA data from his computer. The students report their SAT Math
scores. The following table shows the data for each student in the two classes. Note that the two data values in each row
come from a single student.
Did Mr. Starnes stack his class? Give appropriate graphical and numerical evidence to support your
conclusion.