How many possible 2 card draw combinations are there in 2 decks of cards?

Accipiter22

Banned
Feb 11, 2005
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say I'm playing a card game with 2 52 card decks...plus 2 jokers in each deck, so that's 108 cards altogether...what are the odds of any 2 cards being drawn at a time?
 

RaynorWolfcastle

Diamond Member
Feb 8, 2001
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Are jokers wild?

Assuming that you just want to draw two identical cards, it's simply
1/103

edit:simplified the original eq by supposing that permutations were fine.

Basically regardless of what card you're given, there's a 1/103 chance of getting an identical one
 

Special K

Diamond Member
Jun 18, 2000
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Originally posted by: UncleWai
Originally posted by: Special K
1/nCr(108,2) = 1/5778 = 0.000173

No..... the initial card can be anything... plus this is just wrong.

Well there's 108 choose 2 different pairs of cards in the deck, so why wouldn't that be the probability of any particular pair of cards being drawn?
 

UncleWai

Diamond Member
Oct 23, 2001
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Originally posted by: Special K
Originally posted by: UncleWai
Originally posted by: Special K
1/nCr(108,2) = 1/5778 = 0.000173

No..... the initial card can be anything... plus this is just wrong.

Well there's 108 choose 2 different pairs of cards in the deck, so why wouldn't that be the probability of any particular pair of cards being drawn?

2/108 * 1/107 is your answer right. What you are saying in your calculation is that the initial drawn card has to be one of the two specified card. What the OP is asking is drawn any same 2 particular cards. Think of this as two processes, you draw an initial card first, then the second draw has to be identical to the initial card. Your probability becomes 108/108 (drawn any particular card)* 5/107(match the initial card).
The probability is more than that with 4 wild jokers in the deck, I still haven't thought about it.
 

rikadik

Senior member
Dec 30, 2004
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This depends on some things we don't know:

Are the jokers 'wild'?
Do all the jokers count as the 'same' card, or are there two types of joker (e.g. a black and a red joker)?
 

esun

Platinum Member
Nov 12, 2001
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I think the question is: given any two cards (e.g. J diamonds, 10 hearts), what is the probability to pick those two out of a deck on the first try without replacement?

In which case, (2 / 108)(1 / 107), assuming each card is unique.
 

engineereeyore

Platinum Member
Jul 23, 2005
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Originally posted by: esun
I think the question is: given any two cards (e.g. J diamonds, 10 hearts), what is the probability to pick those two out of a deck on the first try without replacement?

In which case, (2 / 108)(1 / 107), assuming each card is unique.

Wouldn't it be (2/108) * (2/107) since there are two of each card? Shouldn't it depend on if the cards needed are the same? So it could be either (2/108)*(1/107) or (2/108)*(2/107), depending on whether the needed cards are the same (first case) or different (second case).

Feel free to correct me though.

EDIT: Plus, if you have 4 jokers, 2 from each deck, wouldn't that change things also?
 

KoolAidKid

Golden Member
Apr 29, 2002
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I am assuming that you are asking what are the odds of getting a pair. If so:

p(pair) = [p(pair | a joker is drawn as the first card)*p(a joker is drawn as the first card)] + [p(pair | a joker is not drawn as the first card)*p(a joker is not drawn as the first card)]

= [1 * 4/108] + [11/107 * 104/108] = .037 + .099 = .136