Write SQL query to solve given problem: What is the occupation of customers within number of inhabitants ranges of 30 to 40?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT DISTINCT T1.OCCUPATION FROM Customers AS T1 INNER JOIN Demog AS T2 ON T1.GEOID = T2.GEOID WHERE T2.INHABITANTS_K >= 30 AND T2.INHABITANTS_K <= 40