Everybody should know that number of inhabitants is an integer. In case somebody has forgotten it is explicitely recalled in the description by : (** number of inhabitants is an integer **).

When I print the inputs, it only shows up for the test cases I got right and not for the one(s) I got wrong.

Wrong. With your printing you got:

1000
2.0
50
1214
3 should equal 4

which clearly shows the parameters, your result and the expected result.
I understand your frustration for having passed a lot of time in a simple 7 kyu kata but I confirm that "iT's nOt a KaTa iSSuE" and "tHoUsAnDs oF pEoPLe DiD iT jUsT FiNe BeFoRe yOu iN yOuR LaNguAgE.":-)
Cheers and good luck in coding.