A university has an enrollment of 28,422 students. Of this total number, 23,107 are undergraduate students and the rest are graduate students.

A university has an enrollment of 28,422 students. Of this total number, 23,107 are undergraduate students and the rest are graduate students. The school of Engineering has 4,349 undergraduate students and 673 graduate students. A student is chosen at random among the 28,422 enrolled students.

(a) Find the probability that it is a graduate student.

(b) Find the probability that it is an engineering student.

(c) Given that it is an engineering student, find the probability that it is a graduate student.