Answer :
The order would be {-4, -3.2, -0.1, 1.9, 2.3} so the middle number is -0.1. How are you not understanding this?
[tex]The\ order\ from\ least\ to\ greatest:\{-4;-3.2;\boxed{-0.1};\ 1.9;\ 2.3\}\\\\Answer:The\ middle\ number\ is\ \boxed{-0.1}.[/tex]