A repair person is scheduled to be at your apartment between 9:00 am to 12:00 pm but you have to leave at 11:30 to help out a friend. If the repair person is equally likely to be at your apartment any time during the appointment time, what is the probability that you will be there?

5/6 chance

Step-by-step explanation:

If we were to look as 1 hour as a 2 halves, and we have 3 hours, from 9 to 12, we can do 2 halves x 3 hours to equal 6, thus have a probablity out of 6. If you were to be there without leaving, there would be 6/6 times, meaning you wouldn't miss him, but since there is a half hour you are gone, the fraction then becomes 5/6 instead of 6/6. In this case, there is a 5/6 chance that you will be home the same time the repair person comes.