Consider the regression model

GPAi = 0 + 1Blacki + 2Femalei + 3Dormsi + 4Psychi + ui

,where Blacki is equal to 1 if student i is black and 0 if otherwise, Femalei is equal to 1 if student i identifies as female and 0 if otherwise, Dormsi is equal to 1 if student i lives in the dorms and 0 if otherwise, and Psychi is equal to 1 if student i is majoring in psychology and 0 if otherwise.

(a) Who forms the reference group in this regression? Be precise. (3 points)

(b) What is the average GPA of the reference group? (2 points)