A researcher is interested in whether number of hours of studying per week predicts college GPA. The researcher also is interested in whether number of extracurricular activities and number of roommates adds to prediction of college GPA, once number of hours of studying per week is taken into consideration. The researcher collects data from 35 university students and conducts a multiple regression entering number of hours of studying into the model first. He obtains an R squared of R2= .43. Next, the researcher enters number of extracurricular activities and number of roommates into the regression model. He obtains an R squared for this new model with all three predictor variables of R2= .57.

1. What type of multiple regression did the researcher conduct?
2. Calculate R squared change.