For the last decade, Alexa Merschel, 39, has been recruiting college students to work at professional services giant PwC. She’s hired more than 500 people. In the process she’s reviewed some 8,000 résumés and interviewed thousands of candidates. She now serves as PwC’s campus recruiting leader, supervising colleagues across the country. I talked to her about what PwC looks for in the students it hires on campus.