Chamilo LMS

I think there already is a topic on this but can't find it using the search tool...
The idea is to be able to have categories used when a test is generated.
For instance I have an exam based on a pool of 100 questions, but presenting only 70 of them.
I'd like to ensure that I have a certain amount of questions presented by category.

In the mean time, when the exam is reviewed, if I select to not show the answer, I'd like the trainee to have a percentage or a score for each category so He knows where He most failed.

This could be added as a multiple choice (dropdown box) with a number to select in the scenario of the exercise.
The most difficulty I see here is to be able to give a number of question per categories (and if the number used is higher than the number of existing question in the specific category, then 100% of the questions are used.

We could avoid having the field "Ordre des questions aléatoire", but have a total field that increment according to the number of qustions used per category.
A default category would then exist (such as misc.)so if there is no category specified for questions they are shown under the default cat.

I hope this message is clear, as I know what I expect but it's not really easy to explain :)