1 stat question

y=2.5+ 0.0055X1 + 0.0107X2 +0.00853X3

Gpa X3

Hours spent each week X2

IQ X1

For which independent variable does a unit change have the least effect on gpa?

Assuming other independent variables are held constant how much does gpa increase if the numbers of hours spent studying per week increased from 25 to 30?

What is the predicted graduate school gpa for a student whose IQ of 118, 25 hours spent studying per week and an undergraduate gpa of 3.2