Please answer the following question using set notation (i.e. defining events and all the assumption being used):
Given a class with equal number of male and female students, we have that
probability of male passing an exam is say, $p$ and probability of female passing an exam is say, $q$ what is the probability that a randomly selected student passes the third exam?
Note: student drops out if he/she fails an exam, thus cannot appear for the next exam.