The Undergraduate Data sheet of the file P10_21.xlsx contains information on 101 undergraduate business programs in the U.S., including various rankings by Business Week. Use multiple regression to explore the relationship between the median starting salary and the following set of potential explanatory variables: annual cost, full-time enrollment, faculty-student ratio, average SAT score, and average ACT score. Which explanatory variables should be included in a final version of this regression equation? Justify your choices. Is multicollinearity a problem? Why or why not?