How to: special case of grading quizzes

Scenario: You are giving students several learning quizzes throughout the semester.  Each quiz has a fixed number of multiple-choice questions.  Each question is worth 1 point.
Students can attempt these quizzes unlimited number of times (within a specific time period) in preparation for the midterms and finals.  While you do not particularly care about students overall grade for each quiz you would like to encourage them to attempt and get correct answers to at least half of the questions in each quiz.  Altogether 5 quizzes count for 5% of the final grade, however each quiz has a different number of questions and is worth different percentages: Q1 - 1%, Q2 - 1,5%, Q3 - 1,2% Q4 - 0,8% Q5 - 0,5%

Question: How can you set this up using Moodle Quiz activity and Moodle Gradebook

Logic behind the suggested solutions:

The tricky part of this scenario is identifying whether a student correctly answered less than a half of the questions (no grade) or over a half of the questions (full grade).

One way of doing this is by setting the maximum grade for the whole quiz to 1, irrespectively of number of questions in the quiz, total of marks, and/or percentages. 

This allows to use round function that will round up (to 1) grades from 0.5 and above and round down grades below 0.5  Proper percentages can be assigned to the quizzes via aggregation in the gradebook.

Suggested set up:

• Set up 5 quizzes the way you usually do

• Assign max quiz grade for each quiz to 1

• In the gradebook create a category for quizzes with a maximum grade of 5

• Move 5 quizzes into the category

• Assign ID numbers to each quiz and use the following formula for the calculation of the Quiz category total (q1, q2, q3, q4, and q5 are ID numbers of quizzes)
  
  =round([[q1]],0)+round([[q2]],0)*1.5+round([[q3]],0)*1.2+ round([[q4]],0)*0.8+round([[q5]],0)*0.5