1. A class consists of 10 juniors, 10 seniors, and four graduate students. Agroup of six students is selected at random from this class. Compute the conditional p.m.f. of the number of juinors in the group given that it contains exactly one graduate student.

2. A six-sided dice is tossed once and its outcome is noted. It is then tossed repeatedly until an outcome is observed that is at least as large as that on the first toss. Compute the expected number of tosses needed, not including the first toss.