We have to calculate the mean of the given dataset.
We can do it with the expression:
[tex]\bar{x}=\frac{1}{n}\sum_{i=1}^nx_i[/tex]where n is the size of the dataset and xi is the value of each of the elements of the data set.
We can then calculate the mean as:
[tex]\begin{gathered} \bar{x}=\frac{1}{15}(8+12+15+9+10+12+12+18+14+15+10+11+12+9+17) \\ \\ \bar{x}=\frac{1}{15}(184) \\ \\ \bar{x}\approx12.3 \end{gathered}[/tex]Answer: the mean of this dataset is 12.3.