Step-by-step explanation:
The mean absolute deviation of a dataset is the average distance between each data point and the mean. It gives us an idea about the variability in a dataset.
Lets first find the mean of the data set:
![Mean=(8+21+19+18+11+22+20)/(7)=17](https://img.qammunity.org/2023/formulas/mathematics/college/er21i5k6glr5l92bnwngv3oyqamhk63e45.png)
Now for the mean absolute deviation we have to find the absolute distance from each value and the mean, the MAD formula is:
![MAD=\frac{\sum_{i\left|x-\bar{x}|\right?}^{}}{n}](https://img.qammunity.org/2023/formulas/mathematics/college/huwtluei0qjydgkpz2diizms396v2gsnd8.png)
In this case:
![MAD=(\left|8-17\right|+\left|21-17\right|+\left|19-17\right|+\left|18-17\right|+\left|11-17\right|+\left|22-17\right|+\left|20-17\right|)/(7)](https://img.qammunity.org/2023/formulas/mathematics/college/cwgngajqu3o5fg8y3yqiwilir9w6xqrj4l.png)
![MAD=(9+4+2+1+6+5+3)/(7)](https://img.qammunity.org/2023/formulas/mathematics/college/funu9jpesclwhzzdnl8gqq4m8wbzfdf68q.png)
![MAD\approx4.2857](https://img.qammunity.org/2023/formulas/mathematics/college/pt96uhfjq6nz4su0yi54d3cozhqinvuk8r.png)
ANSWER
The mean absolute deviation for the data set is approximately 4.29