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Need help on calculation of chance

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Anonymous

Hi all,

I'm quite new on this forum although I've been reading your posts for some time before registering.

I'm designing a card game where all players have to bid cards from their hand to collect those cards with which they can make good scoring hand of 5 cards. at the end of the round each player will have (in a 3 player game) about 1/3 of the deck. The deck consists of 55 cards of 5 suits with 13, 12, 11, 10 and 9 cards each numbered from 1 to x, where x is the # of cards in the respective suit. The reason for the unequal # of cards in each suit is to eliminate the chance for a draw.

Now for the statistical question, I know some statistics and some chance calcutaions but most is done intuitive. For the scoring at the end of the round I opted to use the rarity of the combination for determining which hand wins:

(from top to bottom)

1) 5 of a kind.

-There are 9 possible combinations (remember only the numbers 1-9 are present in each suit).

2) straight flush of 5.

-There are 35 possible combinations (9+8+7+6+5)

4) straight flush of 4.

-There are 1970 possible combinations (10+9+8+7+6 = 40 of these there are 10 combinations where only 1 possible card is needed to makes it a straight flush of 5 (1 to 4 or 10 to 13 f.e.) and 30 combinations needing 1 of 2 cards (2 to 5 etc.) so 10 * 50 (55 - 4 (the cards making up the straight) - 1 (the possible card making it a straight of 5) + 30 * 49 (55 - 4 -2 (the possible cards making it a straight of 5 ) --> 500 + 1470 = 1970.

3) 4 of a kind.

-There are 2300 possible combinations (((9 * 5 (for each combination of 1-9)) + 1 (4 cards with 10)) * 50 (55 - 4 (the 4 cards that make up the 4-of-a-kind) -1 (the card that will make it a 5-of-kind)))

So 5 of a kind wins from straight flush of 5 wins from straight flush of 4 wins from 4 of a kind, to me this seems intuitively wrong (being from a scientifical background I know that feeling intuitively wrong means, as much as not, statistically correct). this derivation from the "normal" poker-like scoring can probably be attributed to the unequal suits in the deck.

Are my calculations (or rather, is my approach) correct? Is more number crunching needed to take into account that each player can choose their 5 card hand from about 18 cards in their hands?

If those that have a firmer grasp on statistical calculations than me could help me here I would be greatly appreciated.

Arjen

Qundar
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Joined: 12/31/1969
Need help on calculation of chance

Hi,

*rubs head* Ow, this makes my head hurt. Sorry, can't help you there. I know there are those around here who can. Where are they I wonder?

Live long and prosper, Qundar out.

Emphyrio
Emphyrio's picture
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Joined: 02/10/2010
Need help on calculation of chance

I'm not a statistician either, but I follow your reasoning and it seems correct to me (except I think there are 2301 possibilities for 4-of-a-kind -- for the combination of 4 10's, you could have any of the other 51 cards in the 5th spot).

I think the reason your ordering diverges from poker hand ranks is that you have 5 suits, not that they are different sizes. If you do the same calculations for a deck of 5 equal suits of 13 cards each, you get the same ordering:

5 of a kind -- 13 possibilities
Straight flush of 5 cards -- 45 possibilities
Straight flush of 4 cards -- 2960 possibilities
4 of a kind -- 3900 possibilities

It's the fact that for each 4 of a kind you have 5 combinations (because of the 5 suits) that makes it different from 4 of a kind in poker.

As far as being able to choose your best hand, I don't think it changes the relative ordering, since the number of possible hands of each type is still the same -- you just have more chances of getting one.

nomadsgames
nomadsgames's picture
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Joined: 07/27/2008
Whats wrong with a draw

I'm in the same corner as Qundar. All of this is abit above my head.

But just a comment, "I see nothing wrong with a chance of a DRAW". Have you calculated the probability of a draw?

A couple games i can think of that can end a draw - Chess, Blackjack (push) and tic tac toe (cat's game).

Just my 2 cents

NoMADsGames

jwalduck
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Joined: 09/06/2011
Need help on calculation of chance

You have crunched the numbers on your own game, have you crunched the numbers on regular poker hands? Maybe they are out of order frequency-wise.

Emphyrio
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Joined: 02/10/2010
Need help on calculation of chance

The ranking of regular poker hands does reflect their frequency. See, for example, http://www.poker1.com/mcu/tables/Table12.asp

TrekNoid
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Joined: 10/02/2009
Need help on calculation of chance

One site for calculating combinatorics of poker hands is Dr. Math....

http://mathforum.org/library/drmath/sets/select/dm_poker.html

Maybe you'll get something there that you can generalize to your problem?

Trek

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