Answer: because 1.8 is an outlier.
Explanation: it can been seen that from the data given to us, 1.7, 1.8, 1.9, 1.9 are all close to each other with a difference of 0.2 or 0.1.
By considering 0.8, this value (0.8) is at a very far distance away from other observational data with a difference of at least 0.9.
This henceforth makes 0.8 an outlier ( a data which is at a far distance away from other observational data)
