2) A high school janitor has 140 keys on his key chain. Of these 140 keys, 90 open
classroom doors, 80 open the door to the teachers' lounge, and 50 open classroom
doors and the teachers' lounge.
Using this information, answer each of the following questions. Let C be the event that a
randomly selected key opens a classroom and T be the event that a randomly selected
key opens the teachers' lounge.
a) What is P(C), the probability that a key opens a classroom?
b) What is P(T), the probability that a key opens the teachers' lounge?
c) What is P(C and T), the probability that a key opens a classroom and the
teachers' lounge?
d) What is P(C or T), the probability that a key opens a classroom or the teachers'
lounge?