Math quesion

Cloodie · #1 07-30-2007, 04:15 PM

I'm reading Hilger's Texas Hold'em odds and probabilities and can't get some of the calculations to work out. For example....

The odds of getting dealt Aces twice in a row is 0.0045 x 0.0045 = 0.00002. (all well and good so far). The part I don't get is where he works out the odds by taking the inverse and subtracting 1 giving 49,383 to 1.

When I do that calculation I get 49,999. Where am I going wrong?

With other calculations it seems to work out fine (i.e. if the probability of something happening is 0.02 then 1/.02 - 1 = 49 to 1)

AngusThermopyle · #2 07-30-2007, 04:44 PM

Odds of getting AA once is 1 in 221
(1/13 for the first card to be an Ace,
3/51 for the second card to be another Ace,
1/13 * 3/51 = 3/663 = 1/221)

or

0.0045248868778280542986425339366516

so .0045 is off due to rounding.

Odds of getting AA twice is 1 in 221 * 221 = 48841 or

.000020474601257140517188427755369464

1 in 49383 and 1 in 49999 are both wrong.

Cloodie · #3 07-30-2007, 04:49 PM

I knew my figure was wrong but I'm trying to do the calculations based on the methods shown in the book. The fact that I can't get the same answer for what should be a fairly simple calculation is a worry.

UATrewqaz · #4 07-30-2007, 04:52 PM

.0045 x .0045 is actually 0.00002025, that extra little bit you are losing in the rounding to .00002 is the cause of the wrong figure

1 / .00002 = 50000

1 / .00002025 ~= 49383

Cloodie · #5 07-30-2007, 04:55 PM

Ah, thanks for that. Problem is I was following the example in the book which gave you the rounded up answer of 0.00002 rather than doing the calculation from scratch myself.

Lego05 · #6 07-31-2007, 12:39 AM

I guess you already got your answer, which is good cause I don't know how to do this and I don't feel like thinking about it cause I have a better question:

Who cares? Why do you need to know this? How is this gonna hekp you play poker better? If this is you studying I think you are wasting your time.

Cloodie · #7 07-31-2007, 02:17 PM

A valuable contribution there.....

7n7 · #8 07-31-2007, 03:09 PM

[ QUOTE ]
I guess you already got your answer, which is good cause I don't know how to do this and I don't feel like thinking about it cause I have a better question:

Who cares? Why do you need to know this? How is this gonna hekp you play poker better? If this is you studying I think you are wasting your time.

[/ QUOTE ]

Kind of like the amount of time it took you to post this.

Nothing wrong with someone trying to understand the math behind probabilities or doing it for the practice.