Puzzling statistics

Let’s take an imaginary HL deck.

Tell me what position you think Zephrys is in (1-30), and then I turn over 28 cards, which are not Zephrys, leaving only two cards not revealed - the one you picked, and one other.

With two cards left, what are the odds that your card is Zephrys?

(Don’t rush to the 3 door puzzle, this is not quite the same)

1/30, since “my card” is the position you had me guess and doesn’t depend on anything you do after that.

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just google “the three door probability problem”, the probability for the chosen card wont change regardless of how you try to maniplulate it

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No correct answers yet

2 correct answers so far and one poor attempt to claim the game is rigged :slight_smile:

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one in 30 is correct

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That’s only because what you think you’re asking isn’t what the text of your post says.

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Bro shortly, after drawing 28 not Zef cards, there are 2 cards left, its 50-50.
Guys 1-30 its about when you chose the card or not.
But to draw a Zef, its 50 :stuck_out_tongue:

wrong. the three door probability problem tells us that when you pick your card at 1/30 that card has the probability 1/30, when you then remove the incorrect choices your card still has the probability 1/30 while the 2nd card ends up with a 29/30 probability

the 1-30 is the base for the probability problem, for your scenario you cant pick a card before removing the other cards

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No, because you cant change your pick at those 2 cards that are left.
your chances where determined in those 30 cards and it doesnt matter if he removes 28, your probabillity is still 1/30

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And still no correct answers!

The answer is, it depends on how the cards are selected. If I turned over 28 cards at random, then it’s 50/50. Otherwise it’s 1/30.

This is relevant when you consider how cards are selected when being drawn.

incorrect, please read up on some probability theory before you attempt a probability discussion. the key action is that you made someone pick a card, not how you turned over the cards.

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But you didnt

Maths and humans will always be troubling.

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I deliberately omitted the detail I used to turn over cards. This is why 5/30 != (1-30)+(1/29)…(1/26). You’re not really my target audience

And here’s the actual correct answer.

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Suppose the case with a deck of 30 cards.
You draw 28 cards, from the top , one by one. None is Zephrys. Only 2 cards in deck.
So whats the probability of zef being as 29? Its 1/30. Whats the prob of zef being as 30? 1/30.
But here is the question.
What is the prob to draw zef, its 50-50 qs it shares the same prob to be 29 or 30.

that logic only works if you didnt pick a card, by picking a card in belief that it might be zeph you lock that card into a 1/30 probability reagardless of what actions you take afterwards, meaning if you picked cards 29 then card 30 has a 29/30 chance to be zeph

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your target audience are people that dont know how probability works? regardless that doesnt change the fact that your logic is wrong.

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No you where very specific with your choice of words by saying that you would turn over 28 cards that are not zephrys.

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the formulation is the very basis for a three door probability problem