In this question, all number is having 9 as the biggest digit and the longest number have 3 digits on the right of decimal point. It will be easier if you multiply all the number by a thousand (because thousand have 3 zero). The resulting number would be:
9129
9370
9300
9219
Looking at those number, it is clear that the order would be
1. 9.370
2. 9.300
3. 9.219
4. 9.129