Problem #4: (20pts) (a-b) 10 pts You arranged a meeting with your friend in QU library between 12:00 - 13:00. a) You agree that both of you will arrive in a random time between 12:00 - 13:00 and upon arrival you will wait precisely 15 minutes, and then leave if you cannot meet with him/her. What is the probability that you will meet with your friend? b) You want to make sure that you are likely to meet with a probability higher than 50%. How much time you should wait at the least?