Chance of Being Ahead or Behind by 20% From Where I Am Right Now at End of Year

[Midwest Player]

For some reason I'm having a great year at blackjack and sp21. I waiting for it to turn and head the other way, but so far it hasn't. If I would quit right now for the year, this would be my 2nd best year lifetime.

Anyway lets assume one is up $25,000 at this point in the in year. (I'm actually up more than that.) I will give a rough figure of 800 hours of play to go for the rest of the year. Betting levels are anywhere from $10 to $100 depending on the play-thru requirements. A small promotion is usually a $10 to $30 playing level. A $100,000 play-thru promotion usually requires mostly a $50 bet with a few $75 or $100 bets thrown in. Very seldom do I make a bet over $100. Games usually have a .4% house edge. Any idea of the probability of being in the range of + or minus 20% from where I'm right now.

[JohnGalt007]

Any idea of the probability of being in the range of + or minus 20% from where I'm right now.

Depends on the rules of the play-thru promotion and the standard deviation of the games you're playing. If you have both, you can figure out the probabilities of being within the interval [-20% of $25000, +20% of $25000]; this is a confidence interval with known upper and lower bounds and unknown confidence levels.