I hope this is the right place to ask this question as it is related to probability and stats.
Basically, we were supposed to have final exams in the form of a written one, yet due to the pandemic, it was changed to a remote multiple-choice test. The test had 30 questions, each question got 4 choices (only 1 correct answer). Choosing the wrong answer will cause a student 1/3 mark deduction. The thing is, once a student tick to any answer, they aren't allowed to untick to make that question become blank to avoid a possible 1/3 mark losing.
To me, I think it was an issue. But when I complained about this issue with the guy who's been in charge, he responded to me that the setup of not letting student uncheck their answers, on average, will not disadvantage students. He also said that statistically, choosing not to answer or choosing to give random answers would make no difference as the average total score would still be zero.
I found it not correct. I think the situation he explained to me only correct when the number of questions students randomly choose is a big number. In that case, choosing randomly answers or leaving the answers blank will be as he claimed. But in the real exam, students often had a small number of questions they were not sure about, like 5 or 6 questions, and randomly choosing with 1/3 mark penalty for the wrong answer would put students in the disadvantage than otherwise.
Please help me to explain to me if I get it right or not? Thank you.