Exams are not a problem, anybody can pass all the tests. I don't want to disappoint you but in most cases If you are not Qatari National, it is very hard to get hired in admin department. Even if all formalities are done, CID will be the last one to hammer on your head and will reject it.
Most of the admin posts are specified for Qatari Nationals. I experienced it already, but I was lucky, only the HR rejected it, otherwise, I should have lost my present job also, if rejected by CID.