Stop-n-Go question

spectre

wayfarer wrote:

I was looking at it there and I got 43% again. Using the same symbols as you did

P(A) = ... = 0.5
Like you have

For the other two I worked it out a different way coz I hate that 'C' thing, and it doesnt work for google. It ain't pretty but its effective.

P(B) = 0.5*[3*(3/48)*(34/47)*(33/46)] + 0.5*[3*(4/48)*(34/47)*(33/46)] = 0.1135
You forgot to take into account the fact that half the time your opponent won't have a K and that it will be in the deck

P(B|A) = 3*(3/48)*(34/47)*(33/46) = 0.0973
Same as your anwser

P(A|B) = P(B|A)*P(A) / P(B) = (0.0973*0.5)/(0.1135) = 42.863%

42.857% was the other one but the difference is more than likely just from rounding off the numbers.

Right you are wayfarer. I was thinking that my answer sounded a bit too low.
Well done

gerire

OK nuf of all this wheres Dev to answer for his sins????????????

Well explained maths btw wayfarer

peaderfi

wayfarer, you are right my post is wrong and this is the first time i've actually had a chance to read over my post since i'm in the middle of exams and have just spent the past two days without internet (it went kaput shortly after i posted because i tripped and pulled my router down onto the ground breaking its case open

in my original post

the plus here

((14 - x)*4) + 2

and here

(50 – ((14 – x)*4) +2) = 48 - 14*4 + 4x = 4x - 8

should have been a minus

so it should really be

(52 - 14*4 + 4x) = 4x - 4

so which means that you also made an elementary adding mistake in your post as follows

wayfarer wrote:

In that part, there is the same number of combinations of undercards in the deck as there is in the first part ie. according to his formula '(4x - 6)C3'. So the probability of a flop of undercards when you are holding TT and your opponent has overcards is:

(4x - 6)C3 / 48C3 = 34.6%

the probability of a flop of undercards when you are holding TT and your opponent has overcards is:

(4x - 4)C3 / 48C3 = 41.28%

but that is neither here nor there because either way though it means that in fact i was wrong and it reduces the chance of overcards falling...i apologise for this

now as opposed to being especially grumpy bout me making a mistake in adding why don't you take into account that it was 4am when i posted it...

now onto your comments about me

wayfarer wrote:

I honestly can't believe he typed this out and didn't give a second thought to it![/wayfarer]

i did think that it was very wierd and did have a good think about it but i couldn't see the mistake of the plus being a minus and thats why i stuck in that sentence...so don't comment on something which you obviously don't know anything about (ie my thought process or the length of time i thought about something because i spent the better part of half an hour looking over thinking that it couldn't be right but like i said i was tired and didn't see my mistake)

in answer to your earlier post yes the original post is enough but i figured that i would go ahead anyway and try do a general post for if you hold any pocket pair what the chances of overcards coming is...and so provide a post which may be useful in general to people, so i was partly answering his post but mainly doing the general thing.

now that i'm done with that bit, wayfarer you are correct bout there being a 43% chance that your opponent holds a king assuming he definitely holds overcards...now back to my studying

wayfarer

peaderfi wrote:

in my original post

the plus here

((14 - x)*4) + 2

and here

(50 – ((14 – x)*4) +2) = 48 - 14*4 + 4x = 4x - 8

should have been a minus

so it should really be

(52 - 14*4 + 4x) = 4x - 4

so which means that you also made an elementary adding mistake in your post as follows



the probability of a flop of undercards when you are holding TT and your opponent has overcards is:

(4x - 4)C3 / 48C3 = 41.28%

So when you're holding TT, the number of undercards (incl. the other two tens) in the deck is, going by your new formula

= 4x - 4, where x = 10
= 4*10 - 4
= 40 - 4
= 36

but 4 twos, 4 threes, 4 fours, 4 fives, 4 sixes, 4 sevens, 4 eights, 4 nines and 2 tens = 34

Can you have a look at it again?



It doesnt really matter to me what time you posted it at or what your thought process was, all I'm looking at is the post. You could have just left it to the morning if you felt that you were getting it wrong.

The reason I was pretty peeved was because I hate maths like this. I find that its not only very easy to make mistakes when doing, but also its quite hard to follow and to check if its correct. And in the end, I don't think the result is worth much when you compare it with other ways of working out the anwser (like the way that was used at the start of the thread). Its much easier to count the number of cards using your fingers and stick a simple calculation into google rather than learning off a couple of peculiar formulae. And in my experience you'll be right more often too.

Another thing is less people who read the board will be able to follow this compared to using other methods. You should be aiming to make posts that will benefit the majority of the readers here. It took me a sec to remember what 'C' stood for and the only reason I went back and had a look over your numbers was because of the bit that I quoted earlier in the thread