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Probability (reddthat.com)
submitted 3 months ago by to c/mathmemes@lemmy.blahaj.zone
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[–] 15 points 3 months ago (13 children)

I would answer C) 0% - Ultimately I feel this isn't a "pick the correct answer" type of test and more of a "pick the best answer" type of test.

My reasoning is there are really two questions - one is being answered at random, the other I am answering. The one being answered at random is making any answer it chooses wrong - If it picks A or D (25%), then the correct answer is B (50%). If it picks B (50%), then the answer is either A or D (25%). If it chooses C (0%) then the correct answer is A or D (25%) again. No matter which one is chosen at random, it becomes wrong as soon as it is chosen. So then back to the question on the test that I am answering, the correct answer is C) 0%.

Also, if the teacher marks that wrong, then I am even more correct.

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  • [–] 8 points 3 months ago* (last edited 3 months ago) (7 children)

    You can’t separate the question like that. Whichever answer you circle indicates your assertion that this is the probability of getting the correct answer by uniform random chance.

    This means that any answer you circle is wrong, and so the correct answer is to not circle any of them. You could even write e) none of the above to indicate that you have deliberately chosen not to circle one of them instead of skipping the question.

    I have had plenty of exams with multiple choice questions that included the possibility of no correct answers, one correct answer, or even multiple correct answers, and we were expected to make that judgement (rather than blindly follow instructions).

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  • [–] 3 points 3 months ago (2 children)

    What multiple choice test includes questions with no correct answer? That seems stupid to me.

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  • [–] 3 points 3 months ago* (1 child)

    They’re called multi-select questions and you’re warned about them by the professor ahead of time. Sometimes they have a “none of the above” option but sometimes they don’t.

    The purpose is to get you to think critically. If you look at a question and all of the options seem wrong to you, making a guess because “one of them has to be right, it’s multiple choice” is lazy thinking and has nothing to do with the subject matter. In real life you don’t have the luxury of knowing that there’s one correct answer among a set of options.

    The purpose of an exam is to test your knowledge of the course subject, not to test your ability to take multiple choice tests. Sometimes that’s hard to separate out, but the standard multiple choice question (where one and only one answer must be correct) is very game-able by guessers who don’t know the subject very well and risks the possibility of someone getting very lucky while not knowing anything.

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  • [–] 1 point 3 months ago

    Well, I suppose I fell into the trap of thinking that questions with no right answers meant nobody could get a perfect score, but I would imagine that 1) it's fair across the board and 2) accounted for in the scoring somehow.

    I suppose I was always a fan of taking easy multiple choice tests as a student - some people write them such that by using the tiniest amount of logic, someone with zero knowledge of the subject could still probably ace them, versus someone writing a diabolical one that dives deep into the subject matter and has answers that are very very slightly different and you really do have to know the material strongly to have any hope. lol. But taking a diabolical test where some questions don't have ANY correct answers would be even MORE satisfying to ace if you really do know the material well enough, so that sounds like fun. :)

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  • [–] 2 points 3 months ago (3 children)

    The answer is 0%: no matter what you chose, it's wrong. Therefore, at random, you have 0% chance of picking the right answer randomly (or not).

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  • [–] 1 point 3 months ago (2 children)

    If your chance of getting the right answer is 0%, then the right answer is (c) 0%, giving you a 1/4 or 25% chance of being correct, thus the answer cannot be 0%.

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  • [–] 15 points 3 months ago (4 children)

    It’s definitely B ) 50%. Ignoring the values for answers, there can only be 1 “correct” answer. If you have 4 options and 1 can be correct, a random guess is 25%. Since there are 2 options for 25%, you have a 50% chance of guessing the correct 25%.

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