An outlier is a number that is far away or different from the other numbers in a data set. Even if they are close to each other, there might be something else that is different.
Notice that all the decimals EXCEPT for 8.0 and 10.8 have 9 as their whole number. Even if they are near each other, they still have a different whole number. Therefore, the outliers are 8.0 and 10.8