Answer:
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.
