This is one of a whole range of requirements to do with how the final quiz grade is computed. This is really a two-step process: a) Combining the marks from all the questions to get the overall attempt grade (which is what you are asking about here) and then B) If the quiz allows multiple attempts, combining the attempt grades to get the overall quiz grade.
At the moment, A) is always done as a weighted sum, using the maximum mark for each question set on the Edit quiz page; and for B) there are 4 options: first/last/best/average attempt score.
The Moodle-ish way to make this more flexible would be to replace the fixed options with a new type of plugin.
For almost any idea you can imagine, it is not difficult to imagine writing the code that adds up the scores the way you want. (After all, manuipulating number is something computers are very good at.) The more complicated bit is working out how to display the options to teachers, so that they can control things, without the User-inteface becoming even more complicated than it already is.
At the moment, A) is always done as a weighted sum, using the maximum mark for each question set on the Edit quiz page; and for B) there are 4 options: first/last/best/average attempt score.
The Moodle-ish way to make this more flexible would be to replace the fixed options with a new type of plugin.
For almost any idea you can imagine, it is not difficult to imagine writing the code that adds up the scores the way you want. (After all, manuipulating number is something computers are very good at.) The more complicated bit is working out how to display the options to teachers, so that they can control things, without the User-inteface becoming even more complicated than it already is.