this post was submitted on 06 May 2025
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Science Memes

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[–] olafurp@lemmy.world 13 points 1 day ago

You can never answer this question correctly. If the correct answer is 25% there's a 50% chance you guess correctly but that would make the 25% wrong.

But if the answer is the 50% then it implies that 25% is correct which implies that 50% is wrong.

We reach a contradiction for both 25% and 50% making the correct answer to make the whole statement truthy 0%.

[–] bratorange@feddit.org 28 points 1 day ago* (last edited 1 day ago) (2 children)

This can also be used a great example of proof by contradiction: There is no correct answer in the options. Proof: Assume there was a correct answer in the options. Then it must be either 25%, 50% or 60%. Now we make a case distinction.

(A) Assume it was 25. Then there would be two of four correct options yielding in a probability of 50%. Therefore 50 must be the correct answer. -> contradiction.

(B) Assume it was 50. Then there would be one of four correct options yielding in a probability of 25%. Therefore the answer is 25. -> contradiction.

(C) Assume it was 60%. Since only 0,1,2,3 or 4 of the answers can be correct the probability of choosing the right answer must be one of 0% 25% 50% 75% or 100%. -> contradiction.

Because of (A), (B) and (C), it cannot be 25, 50% or 60%. -> contradiction.

[–] Natanael@infosec.pub 2 points 1 day ago

Cheeky answer - the correct answer is a superposition of 25% and 50%, thus you answer it as a multiple choice question

[–] 96VXb9ktTjFnRi@feddit.nl 1 points 1 day ago (1 children)
[–] bratorange@feddit.org 1 points 1 day ago

My client renders this as ( c )

[–] brown567@sh.itjust.works 9 points 2 days ago (1 children)

0%

The only winning move is not to choose

[–] bampop@lemmy.world 1 points 1 day ago

Yeah option b should definitely be 0% for added fuckery

[–] sqgl@beehaw.org 6 points 1 day ago

It was only the next day that I returned to this post realising that "this question" isn't even defined.

[–] moakley@lemmy.world 156 points 3 days ago (17 children)

B.

This is a multiple choice test. Once you eliminate three answers, you pick the fourth answer and move on to the next question. It can't be A, C, or D, for reasons that I understand. There's a non-zero chance that it's B for a reason that I don't understand.

If there is no correct answer, then there's no point hemming and hawing about it.

B. Final answer.

[–] lugal@lemmy.dbzer0.com 61 points 3 days ago

I love this, it shows how being good at (multiple choice) tests doesn't mean you're good at the topic. I'm not good at tests because my country's education system priorities understanding and problem solving. That's why we fail at PISA

[–] shalafi@lemmy.world 21 points 3 days ago

You think like I do. Bet you test well.

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[–] bampop@lemmy.world 2 points 1 day ago* (last edited 1 day ago)

Any answer is correct as long as you don't pick it at random. I'd choose (a) because I'm too lazy to read the other options

[–] Nounka@lemmy.world 2 points 1 day ago

I would think a b c d so 25% O he made a mistake znd forgot to take the bubble answer out. Now we only can pick between aord b c so it would be 33%

Seems my logic is wrong iff i read the rest

[–] qwet@lemm.ee 47 points 2 days ago (1 children)

This is a conundrum wrapped in a turducken, swaddled in nesting dolls.

[–] TimewornTraveler@lemm.ee 11 points 2 days ago (1 children)

lol chill out there buddy it is only self-referential once. maybe twice.

[–] Hazzard@lemm.ee 12 points 2 days ago (3 children)

I'm not certain, I think it's an infinite loop.

I.E. If the answer is 25%, you have a 50% chance, if the answer is 50%, you have a 25% chance, if the answer is 25%, you have a 50% chance...

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[–] Reddfugee42@lemmy.world 97 points 3 days ago (11 children)

This is a self-referential paradox — a classic logic puzzle designed to be tricky. Let’s break it down:

Step-by-step analysis:

  1. How many choices? There are 4 possible answers, so if we pick one randomly, the chance of picking any specific one is 1 in 4 = 25%.

  2. How many answers say “25%”? Two.

  3. That means the probability of randomly choosing an answer that says “25%” is 2 in 4 = 50%.

  4. But if the correct answer is 50%, then only one option says “50%” — which is (c). So the probability of picking it at random is 1 in 4 = 25%, contradicting the idea that 50% is correct.

  5. If the correct answer is 25%, then two options say that — a and d. So the chance of picking one of those at random is 50%, not 25% — again a contradiction.

  6. Similarly, if 60% is correct (only one option), then the chance of picking it randomly is 25%, which again makes it incorrect.

Conclusion: Any choice leads to a contradiction. This is a self-referential paradox, meaning the question breaks logical consistency. There is no consistent correct answer.

[–] Applejuicy@feddit.nl 184 points 3 days ago (21 children)
[–] KammicRelief@lemmy.world 79 points 3 days ago (5 children)

haha yeah, I knew it at the "let's break it down:"
I was like.. I know this voice....

[–] josefo@leminal.space 20 points 2 days ago

"Conclusion:" was the final nail in the coffin

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[–] Kusimulkku@lemm.ee 16 points 2 days ago

Got it right though

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[–] nialv7@lemmy.world 59 points 3 days ago (3 children)

The question is malformed and the correct answer isn't listed in the multiple choices. Therefore the correct answer is 0%

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[–] Tiger666@lemmy.ca 11 points 2 days ago

Thanks for making me laugh all alone in my car before heading in to work. I wish I could give you an award. Cheers!

[–] technocrit@lemmy.dbzer0.com 9 points 2 days ago* (last edited 2 days ago) (2 children)

If you're choosing the answer, then there is 100% chance of being correct. Since none of these answers is 100%, the chance is 0%.

[–] Klear@lemmy.world 4 points 2 days ago

That logic would only hold if I wasn't dumb as rocks.

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[–] xthexder@l.sw0.com 30 points 2 days ago (1 children)

It's probably graded by a computer, and a) or d) is a fake answer, since the automated system doesn't support multiple right answers.

I'm going to go with 25% chance if picking random, and a 50% chance if picking between a) and d).
If it's graded by a human, the correct answer is f) + u)

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[–] OpenStars@piefed.social 24 points 2 days ago (7 children)
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[–] Treczoks@lemmy.world 1 points 1 day ago

Great! I'll hand this to my daughter to annoy her co-students who struggle with probabilitiy ;-)

[–] user86223091@lemm.ee 35 points 3 days ago (4 children)

It's 0%, because 0% isn't on the list and therefore you have no chance of picking it. It's the only answer consistent with itself. All other chances cause a kind of paradox-loop.

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[–] Lucien@mander.xyz 37 points 3 days ago (2 children)

This is a paradox, and I don't think there is a correct answer, at least not as a letter choice. The correct answer is to explain the paradox.

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[–] samus12345@lemm.ee 22 points 3 days ago (1 children)

C, which means A or D, which means C, which means...

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[–] seeigel@feddit.org 11 points 2 days ago (1 children)

What's the correct value if the answer is not picked at random but the test takers can choose freely?

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[–] TacoButtPlug@sh.itjust.works 2 points 1 day ago (1 children)
[–] Thteven@lemmy.world 3 points 1 day ago

When in doubt, C it out.

[–] nuko147@lemm.ee 2 points 1 day ago

I choose 75%

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