The student council at a local high school consists of 10 juniors and 30 seniors who are advised by a teacher. The state Association of Student Councils is holding a conference, and the school has enough funds to send only 6 students. The student council advisor decided that 6 students would be selected at random to go to the conference. The advisor conducted a drawing one night after school and announced the results the next day: 4 juniors and 2 seniors would go. The seniors were concerned that the advisor may not have used random chance to decide because so few seniors were chosen.

(a) How many possible groups of 6 students can be selected?