uses math;
...
function mean(const data: array of Integer):Float;
var
Sum: Int64;
i: Integer;
begin
Result := 0;
if (Length(data) = 0) then Exit;
Sum := 0;
for i := 0 to high(data) do Sum := Sum + data[i];
Result := Sum / Length(data);
end;
Feel free to submit as a feature request in the bugtracker.
Notice that it can easily overflow (eg if data = [maxint,maxint,maxint]), that's probably why there are only functions for floting point data, where that risc is a little less.
Bart