Explanation:
To find out how many times the bell and the light rang at the same time in the first hour of opening, we can use the concept of the least common multiple (LCM) of the two time intervals, which are 2 minutes for the bell and 3 minutes for the light.
The LCM of 2 and 3 is 6, which means every 6 minutes, both the bell and the light will ring at the same time.
Now, to find out how many times this happens in the first hour (60 minutes), we can divide 60 by the LCM:
60 minutes / 6 minutes = 10 times
So, in the first hour of opening, the bell and the light rang at the same time 10 times.