It Has Been Hypothesized That Overall Academic Success for Freshmen

Multiple Choice

It has been hypothesized that overall academic success for freshmen at college as measured by
Grade point average (GPA) is a function of IQ scores (X1) , hours spent studying each week (X2) , and
One's high school average (X3) . Suppose the regression equation is:
Y' = -6.9 + 0.055X1 + 0.107X2 + 0.0083X3.
The multiple standard error is 6.313 and R2 = 0.826.For which independent variable does a unit
Change have the least effect on GPA?

A) IQ scores (X1)
B) hours spent studying each week (X2)
C) high school average (X3)