Add all the A tasks

Task/Averages-Arithmetic-mean/Ada/averages-arithmetic-mean.ada

@@ -0,0 +1,25 @@
+with Ada.Float_Text_Io; use Ada.Float_Text_Io;
+with Ada.Text_IO; use Ada.Text_IO;
+
+procedure Mean_Main is
+   type Vector is array(Positive range <>) of Float;
+   function Mean(Item : Vector) return Float is
+      Sum : Float := 0.0;
+      Result : Float := 0.0;
+   begin
+      for I in Item'range loop
+         Sum := Sum + Item(I);
+      end loop;
+      if Item'Length > 0 then
+         Result := Sum / Float(Item'Length);
+      end if;
+      return Result;
+   end Mean;
+   A : Vector := (3.0, 1.0, 4.0, 1.0, 5.0, 9.0);
+begin
+    Put(Item => Mean(A), Fore => 1, Exp => 0);
+   New_Line;
+   -- test for zero length vector
+   Put(Item => Mean(A(1..0)), Fore => 1, Exp => 0);
+   New_Line;
+end Mean_Main;