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Old 11-21-2004, 11:26 AM
blank frank blank frank is offline
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Join Date: Nov 2004
Posts: 52
Default Re: Help! What\'s wrong with this math?

[ QUOTE ]

I’m trying to figure out how to figure out the Standard Deviation when playing blackjack. Can anyone please tell me if this is the right way to do it?

Example:

1. Playing a game where the house has a 0.5% advantage.
2. 400 hands at $5 per hand for a total of $2000 wagered.

[/ QUOTE ]

Now, I'm not totally up on blackjack, so I may be misinterpreting this. If you assume each hand is independent, and you have a 49.5% chance of winning each one (that's how I interpret 0.5% house advantage), you expect to win n*p hands (400 * 0.495 = 198). Your variance on that is n*p*q where q=1-p (400 * 0.495 * 0.505 = 99.99). Your standard deviation is the square root of the variance, or 9.9995. Call it 10 and you've got a confidence interval of 178 to 218 wins. With +/- $5 as the outcome, that translates to results from losing $110 to winning $90.
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