I have a quiz with 8 questions. Every question can have multiple anwsers. User can pass quiz if 75% of anwsers are correct. This means at least 6 question.

I created quiz where point mark is 6, then I created 8 "multi selection (checkbox)" questions and divided points accordingly e.g if 2 correct anwsers then each gives 0.5 points and if 3 correct anwsers then 0.33 point etc.

Seems OK. But if user filles/checks all checkboxes in every question, she/he gets quiz passed and gets certificate, because point marks is enough.

How to prevent this? How user gets certificate only if she/he knows correct anwsers?

Thank You