Final answer:
To raise one's GPA according to the given regression equation, a student should increase the number of hours they study and not skip classes, since these factors have a quantifiable impact on the GPA, whereas the SAT score is a fixed variable for college students.
Step-by-step explanation:
The correlation between a student's GPA, the number of hours spent studying, and class attendance can be represented by a regression equation.
According to the given equation, GPA = 0.25 x combined_SAT + 0.25 x class_attendance + 0.50 x hours_spent_studying, a student can raise their GPA by increasing the number of hours dedicated to studying and maintaining perfect class attendance, while the combined SAT score is a fixed factor.
Although higher study hours have a more significant impact on the GPA, class attendance also plays a role, albeit to a lesser extent.
Therefore, a balanced approach to not skipping classes and investing more time in studying could result in an improved GPA.
Note, since the SAT score is already set for college students, efforts should be focused on the other two variables which they can control.