jlechuga928
jlechuga928
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January 21st, 2015 at 12:39:50 PM permalink
does anyone know the answer?
Romes
Romes
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January 21st, 2015 at 12:49:02 PM permalink
Here's a FAQ from the Wizards Probability Page on WOO:

"What percentage of hands are suited blackjacks? Six-deck shoe, any suit.

RWR FROM TUSCON, USA

The probability of a suited blackjack in a six-deck game is 2*(4/13)*(6/311) = 0.0118723."

So for 5 decks (not that it will change, but just do the math): 2*(4/13)*(5/259) = .0118, or 1.18%, all the same.

Be sure to leverage the search functionality, or even Google (all I did was type "odds of getting suited blackjack" and the Wizards page was the first hit).
Playing it correctly means you've already won.
studmuffn
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January 21st, 2015 at 12:56:33 PM permalink
To add to Romes response, the probability of a suited blackjack, any suit, on any given hand (6-deck shoe) is about 1.18%. Therefore, the probability of not getting one is (1-.0118)= 98.82% for one hand. For your question, the probability of you not getting a suited blackjack in 100 hands is 0.9882^100= 0.3051. Therefore, your probability of getting at least one suited blackjack in 100 hands is
1-0.3051= 69.49%

This is for 100 repeated trials of taking cards out of a fresh shoe. I'm not sure what is meant by '5 deck shuffler', but if cards are discarded each hand, that will change your probability. That calculation would be rather cumbersome without programming.
Dieter
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January 21st, 2015 at 1:13:42 PM permalink
About 1 in 21 hands will be a blackjack.

About 1 in 4 of those will be suited.

This rough math gets you to 1/84=0.0119 chance of a suited blackjack, which is very close with much less math.
May the cards fall in your favor.
Romes
Romes
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January 21st, 2015 at 1:15:39 PM permalink
Quote: Dieter

... which is very close with much less math.


Dieter, we're supposed to teach the kids that math is fun! =P
Playing it correctly means you've already won.
Dieter
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January 21st, 2015 at 1:36:23 PM permalink
Quote: Romes

Dieter, we're supposed to teach the kids that math is fun! =P



It is! Math is great fun!

... but useful approximations are at least as fun, and quite useful, and often easier to remember.


Every schoolkid should know that (about) 1 hand in 21 should be a blackjack. If you play, that's just something you should know. It should be obvious that 1 in 4 will be suited.

As for accuracy... 1.187% vs 1.190% is darn close. 3 one thousandths of one percent close. Surely good enough for government work.

It's right up there with "pi seconds is about a nanocentury". (Of course, it's actually closer to "square root of 10 seconds", but that's less fun.)

May the cards fall in your favor.
Venthus
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January 21st, 2015 at 1:42:24 PM permalink
Quote: studmuffn

I'm not sure what is meant by '5 deck shuffler', but if cards are discarded each hand, that will change your probability. That calculation would be rather cumbersome without programming.



Based on how the question is phrased, I'd assume that the game is being played out of a 5-deck CSM. If you're not acquainted with them, they're pretty common machines in the US where the cards are fed back into the machine and reshuffled every few hands. Based on what I've seen, I'd estimate that, on average, ten cards will be in the discard at a given time. (Obviously, highly dependent on casino policy, number of hands, etc.)

It's close enough to playing with a constantly fresh n-deck game that the math shouldn't be thrown off by much though.
wudged
wudged
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January 21st, 2015 at 4:50:53 PM permalink
Quote: Dieter

It is! Math is great fun!

... but useful approximations are at least as fun, and quite useful, and often easier to remember.


Every schoolkid should know that (about) 1 hand in 21 should be a blackjack. If you play, that's just something you should know. It should be obvious that 1 in 4 will be suited.

As for accuracy... 1.187% vs 1.190% is darn close. 3 one thousandths of one percent close. Surely good enough for government work.

It's right up there with "pi seconds is about a nanocentury". (Of course, it's actually closer to "square root of 10 seconds", but that's less fun.)



Am I missing pi ~ 22/7 in that image? How could Randall forget that, or is it too obvious?
Dieter
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January 22nd, 2015 at 2:16:50 AM permalink
Quote: wudged

Am I missing pi ~ 22/7 in that image? How could Randall forget that, or is it too obvious?



355/113 is closer. 7 digits of accuracy in only 6 digits.

Or, 4*atan(1) (in radians).
May the cards fall in your favor.
wudged
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January 22nd, 2015 at 5:19:40 AM permalink
Quote: Dieter

355/113 is closer. 7 digits of accuracy in only 6 digits.

Or, 4*atan(1) (in radians).



I agree 355/113 isbetter. 22/7 is just what we were told in some really basic math classes to use as an estimation.

4atan(1) = pi, not an approximation
Dieter
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January 22nd, 2015 at 5:33:08 AM permalink
Quote: wudged

4atan(1) = pi, not an approximation



Yeah, but you've got to carry a trig function with you to use it, and it's got to be accurate.
May the cards fall in your favor.
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