Answer:
The mean should be 12.
Explanation:
To find the mean of a range of numbers, you must simply add all of the numbers together and divide by how many numbers there are in the group.
In this case, I did 15+11+10+11+14+10+15+10+12, which came to be 108. I divided that by 9, since there are nine numbers, which gave me 12.
Hopefully this helps!