22.6 is an outlier for which of the following sets of data?
1. 22.6, 21.5, 23.7, 22.6, 28.9, 22.6, 20.9

2. 2.4, 5.3, 3.5, 22.6, 1.8, 2.1, 4.6, 1.9

3. 20.5, 20.8, 21.6, 22.6, 23.7, 24.5, 25.1

4. 13.6, 31.7, 25.8, 22.6, 18.9, 21.6, 30.5