Tuesday, November 17, 2009

In a Tarot deck of 78 cards, what are the odds of pulling the same card twice in a row?

Mathematically, it's 1:78 to pull a specific card. But what are the odds of pulling the SAME card twice in a row?

In a Tarot deck of 78 cards, what are the odds of pulling the same card twice in a row?
1/78. Assuming you don't mean a specific card (like "the Death card") twice. If you do mean a specific up-front specified card twice, the answer would be (1/78)^2.





But for just ANY card twice in a row, it's the same as one specific card. The first draw can be any card at all (probability: 78/78 = 1/1), then the second draw must match the original card (probability: 1/78).





1/1 * 1/78 = 1/78.





Of course, this assumes you draw "with replacement" (putting back the card after you draw it). Otherwise the probability is 0.
Reply:Tx for answering. Still not sure about this. Especially since I drew the very same card again the next day, freaked me out! What are the odds STATISTICALLY that this would happen to someone? Report Abuse

Reply:2:156
Reply:It's still 1/78 because no matter what card you pull first, your odds of pulling the same one again are still 1/78. Now if you are thinking of a card to pull twice BEFORE your first pull, then the odds are 1/6084
Reply:1:78^2
Reply:1:6084
Reply:1:78.





You can pull any card the first time.
Reply:It's 1 in 78. It works that way because you didn't specify which card. If you draw a card, all that needs to happen for your condition to be met is for that same card to be drawn again. It would be 1 in 6084 if you had a specific card in mind that you wanted drawn twice in a row.
Reply:about 1 in 39
Reply:(1/78)^2 = 1 : 6084


= 0.0164 %
Reply:I think its 1/78 times 1/78 =0.000164366


... (the probability of getting that card the first time, then the probability of getting that card the second time, after replacing it.) I am not sure though...I took stats a long time ago. What do other people think?





Actually never mind, looking at other peoples answers, its just 1/78 (what i said above only applies if u specified what card u were pulling)
Reply:What Dr D said.
Reply:it depends if u put the card back in the deck or not
Reply:The probability of pulling any one card is 1 / 78.





Replace the drawn cardback into the deck and shuffle.





The probability of pulling the same card as from the first pull is 1 / 78.





Since the pulls are independent events, we can multiply the probabilities of the seperate pulls to calculate the probability of pulling the same card twice with replacement.





P(pulling same card twice with replacement)


= (1/ 78)(1 / 78)


= 1 / 6084
Reply:one in 78 . both times.
Reply:You are correct that the pulling any particular card on the first draw is 1/78. If you replace the card and randomly draw again, the chance of getting a particular card on the second draw is also 1/78. To get the joint probability of picking the SAME card in two successive draws you multiply 1/78 x 1/78. The resulting probability is 0.000164. To put this in perspective, if you drew two cards in this way 100,000,000 times, you would draw the same card twice in a row about 164 times!


2 comments:

  1. I don't believe or don't think I did unroll last night my girl friend opened her pack and I drew the same card three times, she shuffled them again itild her to split twice and take the top card, guess what same card, when that happened my eyes openned up as did hers, she was sure I had played a card trick....I wish I did as this was super spooky. No I didn't try again! The card was three men one on a pedelstool with three round symbols on a building. Don't know what the odds of x 4

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  2. After looking up my card is The three of pentacals, now I'll read up ;)

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