Salam Everyone. Firstly thanks to CSS Forum and Members, keep this helpful site lively and on. Those who've succeeded in CSS Exam and now doing a Civil Service Job (or those who know), please tell me what is meant by Quota by "Merit"? Does Merit mean the Toppers? If so then what's been the average (%) passing result of Merit holders/toppers in past. Also other than Merit, if you got hired by provincial quota and for females by their special 10% quota reserved, then what was your Passing % in CSS Result. So as we'd be able to set that as benchmark. For example if I set 75% Result, will it be realistic to achieve? Or either only 60% marks would be enough to get a call for Interview? Thanks a lot for your precious time.

Dear Aspirant, there is a quota of seats for all Pakistan "merit" or consider it as open merit. say there are 7 seats reserved for "Merit" then first 7 position holders will get allocated on this quota.
Secondly about setting target percentage , well that is actually relative to every CE , sometimes it is high scoring and at times over all it is a low scoring result.
In any case you have to be at par if not above with the avg. written marks. 75% in written means you are among the toppers. On avg. if you get around 62%-68% you will have a pretty good chance to land your desired group provided that you score good in the interviews.
Women quota is 10% of seats available for any group. e.g. if a group has 10 seats then 1 seat will be reserved for women, irrespective of the fact that if other 9 seats get occupied by women on merit.

For the written exams for now , work hard and forget about the maths and the probabilities. Your job is to study and leave the probabilities to Allah.