Hello there, and thank you for posting your question here on brainly.
To find mean absolute deviation, (MAD) you have to add all the numbers together, and then divide by how much numbers are in the set.
So we have to do 10 + 11 + 15 + 16 + 18, and then divide by 5.
10 + 11 + 15 + 16 + 18 ===> 70
Now, divide by 5.
70 / 5 ===> 14
The mean absolute deviation is 14.
Hope this helped! ☺♥