Louis inserts a 12-track CD into a CD player and presses the random play button. This CD player's random function chooses each track independently of any previously played tracks.
a)What is the probability that the second selection will not be his favourite track?
b)What is the expected waiting time before Louis hears his favourite track?
c)If Louis has two favourite tracks, what is the expected waiting time before he hears both tracks?

Repeat part b assuming the CD player does not repeat selections.