WS III, Semifinal #1 final hand

Again on the last hand BR1 had the better percentage play by doubling down to correlate with BR2's double. BR1 stood and still won with the less than 50% chance to advance. The last hand situation was as follows:

...........Bank Roll.....Bet...................Cards.....Action

John.....208,750.....50,000+50,000......4+5......Doubles

Jeff......219,500.....50,000...............10+5......Stands

Dealer..............................................2


Stand..........44.8%
Double.........66.0%
Surrender.....44.8%
Hit to 18......46.7%

The way it ended was that John's double down card was a 9 for 18.
The dealer hit with 3+5+3+6 for 19 and so Jeff won anyway.

....................BlueLight

 

I just checked with my 2nd grade math teacher and he said that
3+5+3+6=17 not 19. LOL

Actually it was 3+5+5+6 that means for the right play (double down on hard 15) he was getting a right card (5).

 

Remind me

As I've not yet seen any of the WSOB3, is the DD card face down? Not that it should make a difference to the play by Jeff. Assuming we don't know what the DD cards are, if he stands the dealer has got to beat John, if he DD and loses the dealer has to beat John, if he DD and hits 16 the dealer has to beat John, if he DD to less than John but not stiff he needs either a WW or a LL, if he DD to the same or more than John he's locked the win. By DD he still retains the high and low. Many more ways to win by DD than standing, surely in fact an example of a free DD?

Cheers

Reachy

 

It's face-down, assuming that the player isn't using the "Burger King Power Chip." If the player chooses to use their Power Chip, they're allowed to check the double-down card and if they don't like it, replace it with another one, which they don't get to see. Of course, that also means they don't have the Power Chip anymore.

 

Clarification of Dealer Hand

For the last hand in the 1st semifinal in my previous post I showed the dealer hand as:

Dealer...................................2

Later on in the the post I said the dealer hit with 3+5+3+6 and said the dealer hit to 19.
To now clarify, the dealer up card was a 2 and the down card was a 3. Then the dealer took hits of 5+3+6 for a total of 19. I should have shown the dealer cards (in the standard convention) as 2+3+5+3+6.

Also note anytime BR2 doubles and ends up with a stiff then BR1 should match BR2's total bet with a double of his own, even double hard 19. Splitting a pair like 8+8 or 10+10 should be better. The important thing Br1 must match BR2's total bet. It should also be noted that if Jeff was tied in chips or behind in chips then doubling to match John's bet would be suicidal and would reduce Jeff's chance of winning to 10.2%. BR1 only needs to be 1 chip ahead to double down correctly.

........................BlueLight

 

Splitting 10+10 or 8+8

I totally agree with this part of your statement, but not very sure about other part

If BR1 has a chip lead and matched BR2's Bet (which is the best bet), BR2 has to double for less. In this case if BR1 split 10's or 8's, he/she is giving away the low. It is very complicated to decide what to do with your pair.
And BR1's decision will be based on more than one factors ( BR2's total after doubling, Dealer's up card, etc.).
Sometimes the correct play can be very surprising.

 

Very interesting

Until you (I) look at these situations a bit more closely you don't realise that DD on 19 for BR1 is the obvious thing to do in the situation outlined above. I've figured DD at nearly 5.5% better than just standing. As I said earlier I think this is an example of a free DD. If you DD and bust your probability of winning is exactly the same as if you just stand. Am i right? Would I have known to do that in a game? Well I do now

As for the Double for Less vs. Pair, I like that tactic! I think I remember seeing it before but I'd forgotten about it. Thanks for reminding me !

Cheers

Reachy

 

DD hard 19

To prove that this is not always true, I can show at least one example where doubling a hard 19 is not the best way to play.
Lets say Br1 has a chip lead, betting after BR2 and Both bet max.
BR2 doubled and has 18. Dealer shows T.
What is the right play for BR1?

1. BR1 Doubles and advances when he/she makes 20 or 21 (2/13), and busts (11/13) but dealer beats BR2 (Dealer19,20,21=12.07 + 37.07 + 3.74 =52.88%)
P = 2/13 + 11/13*52.88% = 60.13%

2. BR1 Stands and advances when Dealer makes 18, 19, 20 or 21.
P = 12.07 + 12.07 + 37.07 + 3.74 = 64.95%

As we can see doubling is not always free.

 

Specific

I did say it was specific to the situation described not all similar situations regardless of dealer up card. Thank you for the further analysis though. Also as this is WSOB we don't know what BR2's DD card is. How do you factor that into calculating the probability in the situation you describe i.e. Dealer 10, BR2 9 with a doubled max bet, BR1 19?

Cheers

Reachy

 

BlueLight

Hi

I've been trying to duplicate your figures and I can't seem to manage it (my ignorance not your miscalculation I hasten to add!) so I wonder if you would mind showing your working out so I can see the error of my ways.

Many thanks in advance.

Cheers

Reachy

 

For Reachy

I just calculated the situation when BR2 doubles down his 9, BR1 = 19 and dealer has 2.
There is about 2.4% difference in favor of doubling hard 19.

 

Thanks

Thanks Arlalik . However my question was directed at Bluelight as I can't duplicate his initial calculated values. Maybe you can help show me how those figures were arrived at Arlalik?

Cheers

Reachy

 

Just so you know what I'm doing math wise

The figure I get for standing vs. BR2 DD assuming we don't know what the DD card is is 48.1% (calculated using 6 deck dealer outcomes)

The working out:

For BR1 to win BR2 needs to be beaten by the dealer. If the dealer busts it's an automatic win for BR2 and a BR2 push is no good.

BR1 Wins if...

BR2 DD to a stiff hand and dealer makes a hand - 7/13 x 64.65%=34.8%
BR2 DD to a 17 and dealer gets 18-21 - 1/13 x 50.68%=3.9%
BR2 DD to a 18 and dealer gets 19-21 - 1/13 x 37.24%=2.9%
BR2 DD to a 19 and dealer gets 20-21 - 3/13 x 24.24%=5.6%
BR2 DD to a 20 and dealer gets 21 - 1/13 x 11.84%=0.9%

Add that lot up and it comes to 48.1%.

Before I even try to figure out the probabilites of the other outcomes can you tell me where I'm going wrong?

Cheers

Edit: This is for the scenario BlueLight outlined in his first post.

Reachy

 

For Reachy

Reachy, you are in right direction.
I see few minor mistakes here, but they can add up to a huge difference.
Here are the problems:
1.BR2 DD to 17 and dealer gets 17-21(push is OK)= 5.0%, 1.1% diff.
2.BR2 DD to 18 and dealer gets 18-21(push is OK)= 3.9%, 1.0% diff.
3.BR2 DD to 19 and dealer gets 19-21(push is OK)=11.5%, 5.9% diff.
4.BR2 DD to 19 with probability of 4/13 not 3/13

So if we apply these changes to your formulas, the total will be 56.1%, not 48.1% .

Hope this helps.

 

Push OK?

If BR1 stands on 15 he can't win if BR2 pushes can he? If BR2 pushes BR1 has lost by definition hasn't he and a BR2 push beats a BR1 loss? Am I miles off here? Don't forget the scenario is BR2 hard 9, DD (face down card) vs BR1 standing on hard 15.

BlueLights figures were 44.1% for standing: why are we all getting different numbers? 2 of us are wrong at least, possibly all of us!!! It doesn't help that several different and yet similar scenarios have been discussed in this thread.

Cheers

Reachy

 

Good job Reachy

In some reason I thought we are still talking about the case where BR1=19
You are absolutely right about that.
Now lets go back to your numbers.

BR2 DD and gets stiff 6/13 of the time not 7/13.
That is 6/13 x 64.65% = 29.8% not 34.8%

Also BR2 DD and gets 19 4/13 of the time not 3/13
That is 4/13 x 24.24% = 7.5% not 5.6%

The rest of your numbers are correct.

So the total probability to advance for BR1 = 45%

In my opinion Bluelight forgot to add the Probability of
BR2=20 x Dealer21= 0.9%

45-0.9=44.1

 

Thanks Arlalik...

...for picking up my basic errors - Of course there are 4 tens in a deck, I've no idea why I thought otherwise, and if a hard 9 DD with an Ace its 20 not 10.

Now for the DD calculations!

Cheers

Reachy