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Probability (reddthat.com)
submitted 20 hours ago by DrBanjo@reddthat.com to c/mathmemes
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[-] SCmSTR 7 points 1 hour ago

Lmao that's fucked up hahaha

[-] MathiasTCK@lemmy.world 3 points 2 hours ago

C, if their is a requirement to show your work and random guesses that don't show work get no credit.

[-] Toneswirly@beehaw.org 2 points 2 hours ago
[-] yoriaiko 4 points 3 hours ago

It's B - 50%; either correct (50%) or false (50%), binary 0/1, yes/no, score or not.

[-] Crozekiel@lemmy.zip 7 points 5 hours ago

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.

[-] chonglibloodsport@lemmy.world 3 points 3 hours ago

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 your 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).

[-] dogdeanafternoon@lemmy.ca 6 points 5 hours ago

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%.

[-] lemmyvore@feddit.nl 9 points 4 hours ago

Yes but then 50% would not be the correct answer.

[-] dogdeanafternoon@lemmy.ca 2 points 4 hours ago

I fucking hate this game 😭

[-] Avicenna@programming.dev 2 points 4 hours ago

hah I see what you did there!

[-] balsoft@lemmy.ml 6 points 9 hours ago* (last edited 9 hours ago)

Here's a more fun one:

If you pick an answer to this question at random, what is the chance that you will be correct? Mark at least one of the applicable options.

(a) 20%

(b) 6.25%

(c) 0%

(d) 20%

And as another puzzle, what happens if you swap "at least one of the" for "all"?

[-] Mikina@programming.dev 43 points 16 hours ago* (last edited 16 hours ago)

Couldn't you argue that 0% is correct?

It's a paradox, no of the answers can be correct, so the chance that you pick the correct one is 0%.

Sure, by picking it, it makes it wrong, but you don't care about that.

If you ran a infite monte carlo test on it, you'd end up with 0% correct answers.

Sure, picking the zero makes it not true again, but you don't care about that - it prooves that the statistical test holds.

[-] balsoft@lemmy.ml 2 points 9 hours ago* (last edited 9 hours ago)

If you ignore self-referential nature of the question and stop the iteration at some point, sure, you can argue that any answer is correct.

If you ran a infite monte carlo test on it, you’d end up with 0% correct answers.

That would mean your Monte Carlo test is set up incorrectly because at least 1/4 of the results of the test would be the "correct" answer as per your own argument, thus invalidating it.

[-] yakko@feddit.uk 5 points 11 hours ago

The trick is that there is no paradox, only the implication of one. 'If' being the key word - you're not actually being asked to answer randomly, but you are being subtly trolled.

[-] airbreather@lemmy.world 16 points 15 hours ago

Nah it's a paradox. There's no such thing as just a freestanding Monte Carlo test that you can just "run" - you do actually need to define enough parameters to make it tell you anything.

This kind of self-referential stuff feels like a proof of Gödel's incompleteness theorems with extra steps.

[-] bstix@feddit.dk 10 points 13 hours ago* (last edited 13 hours ago)

The correct answer is to leave all the options unmarked.

If you do pick an answer, then you didn't do it randomly. When not marking the answers, the if-statement has the result of "false", but that's not the question.

If your teacher then asks why you didn't answer it, you can safely and unparadoxically claim that inaction is also an option.

[-] Jyek@sh.itjust.works 2 points 8 minutes ago

The question is not asking you to pick at random. It's asking you to suppose that you do pick at random and to mark the correct answer not at random.

[-] YiddishMcSquidish@lemmy.today 1 points 2 minutes ago

They aren't asking them to pick an answer at random though.

[-] balsoft@lemmy.ml 2 points 10 hours ago

If "no answer" is in the set of possible answers, then it is not a correct answer because there's then a 20% chance of it being picked at random. But usually that's not the case for tests anyways.

[-] naught101@lemmy.world 2 points 10 hours ago

Severe programmer mentality 😂 I like it, but I doubt it would play out in the real world

[-] dis_da_mor@anarchist.nexus 62 points 19 hours ago
[-] arsCynic@piefed.social 24 points 19 hours ago

This. I.e., there is no correct answer.

[-] harmbugler@piefed.social 10 points 17 hours ago
[-] Untamed_Star 2 points 2 hours ago

if c was correct then it would be 25% then 50% and then 25% again ans 50% and 25%

[-] Klear@piefed.world 7 points 15 hours ago
[-] bountygiver@lemmy.ml 8 points 16 hours ago

add a e) 20%

[-] MutantTailThing@lemmy.world 15 points 19 hours ago

Does anyone else smell pancakes?

[-] sudoMakeUser@sh.itjust.works 2 points 11 hours ago

Yeah, that's me. They're ready.

[-] Warl0k3@lemmy.world 11 points 19 hours ago

Trick question: One of the 25s is an imposter.

[-] MJKee9@lemmy.world 2 points 4 hours ago

It's a mimic-dark souls math. If you pick it, the test eats you.

[-] lugal@sopuli.xyz 7 points 14 hours ago

It's actually 2S with S=12.5

[-] jaybone@lemmy.zip 6 points 14 hours ago

And 50 is 5O, where O=0

[-] Zizzy 3 points 15 hours ago* (last edited 15 hours ago)

Its 25%. The rules of answering a question with a set of options is that you may only choose one and only one is right unless explicitly stated otherwise. Anything else is breaking the rules, which as the taker would be disqualifying. If you start narrowing it down, as in "its 25% and theres two so now i need to guess therefore its 50" you are no longer answering the question at random and you have answered wrong. But you do have to make that coin flip. Good luck.

[-] FishFace@piefed.social 1 points 5 hours ago

I've never heard that rule. It sounds like an assumption you're making about the question!

[-] balsoft@lemmy.ml 3 points 9 hours ago* (last edited 9 hours ago)

This is the only correct answer to the question as stated.

That of course opens a second can of worms, since now you are actually forced to "pick the answer at random", now with the probability of 50%. But such double entendres are typically not considered for test questions unless explicitly specified.

[-] dogdeanafternoon@lemmy.ca 1 points 5 hours ago

Yeah, in my opinion the answer is 50%. You got a 50/50 shot at picking the correct 25% answer.

[-] UpperBroccoli 5 points 18 hours ago

The right answer is neither a nor b nor c nor d, but "beer with tzatziki".

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[-] Jambalaya@lemmy.zip 7 points 20 hours ago
[-] fbs@lemmy.world 33 points 20 hours ago* (last edited 20 hours ago)

If the answer is B, that means there's a 25% chance of getting the right one. So the answer is A and D. But wait... that's 50%

50% means 25%

That means 50%

So it's 0% because it's impossible.

Meaning it's 25%

Damn it

[-] Scipitie@lemmy.dbzer0.com 10 points 19 hours ago

Not really but you're thinking in the right direction!

There is no correct answer because the question and the answers exclude themselves:

For four different options it is 25% but here two options are the same - so you have a 50% chance to land on a 25% - but this means that the correct answer is only in one of the four answers, therefore you're having a 25% chance.

It's a nice demonstration of what happens when the answer and question are intervined and any result changes an aspect of the answer - you're fucked, basically.

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this post was submitted on 06 Aug 2026
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