The manager of a bank recorded the amount of time each customer spent waiting in line during peak business hours one Monday. The frequency table below summarizes the results. If we randomly select one of the customers represented in the table, what is the probability that the waiting time is at least 12 minutes or between 8 and 15 minutes? Round to three decimal places as needed.
Waiting Time (minutes)
0-3

4-7

8-11

12-15

16-19

20-23

24-27

Number of Customers

9
10
12
4
4
2
2