# BBO Discussion Forums: Claculation Question - BBO Discussion Forums

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## Claculation Question

### #1onaykk

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Posted 2018-February-12, 03:57

Hello,

I am relatively new in Bridge but I am quite obsessed lately about the claculations and possiblities. I have a problem:

Whenever lets say you have 5 H in the bid and you and your partner has 10 H in your hands. Lets say Hands are A Q 8 7 6 5 in your hand and partner is J 10 9 2 . There is K 4 and 3 out. Lets say turn is yours. In this situation hitting A is a better probability that one of the opponents have K or the bigger percentage is trying to go to your partners hand and try to do Empass , and gambling to get K from the one opponent?
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### #2onaykk

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Posted 2018-February-12, 03:58

If it is 11/ 2 it is very easy to calculate but 10/3 is very tricky.
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### #3helene_t

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Posted 2018-February-12, 05:32

If you are missing three cards including the king, they can be distributed in 8 ways:
K43-void finesse wins
K4-3 finesse wins
K3-4 finesse wins
K - 34 both win
43 - K drop wins
4 - K3 nothing works
3 - K4 nothing works
void - K43 nothing works

So the finesse wins in 4/8 = 50% and the drop in 2/8 = 25%. In fact the drop is slightly better than this because a 2/1 split is a bit more likely than a 3-0 split so it's about 26%.
You might speculate on the psychopathology of some posters but hating them seems excessive --- Nige1
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### #4onaykk

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Posted 2018-February-12, 06:24

2/1 split only changes the odds around %1? That was my main question maybe at least %10?
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### #5onaykk

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Posted 2018-February-12, 06:27

But of course Finesse also wins in 1/2 in common at one of the positions so that also decreases. Thanks a lot.
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### #6NickRW

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Posted 2018-February-12, 06:32

onaykk, on 2018-February-12, 06:24, said:

2/1 split only changes the odds around %1? That was my main question maybe at least %10?

No, nothing like 10%.

2-1 split = 78%. 6 different distributions = about 13% for a specific case
3-0 split = 22%. 2 different distributions = about 11% for a specific case.
"Pass is your friend" - my brother in law - who likes to bid a lot.
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### #7pescetom

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Posted 2018-February-12, 08:00

NickRW, on 2018-February-12, 06:32, said:

No, nothing like 10%.

2-1 split = 78%. 6 different distributions = about 13% for a specific case
3-0 split = 22%. 2 different distributions = about 11% for a specific case.

Surely those are the odds of finding the K on one specific side in the given case of distribution.
I think the OP was looking for the odds of success of the A drop versus finesse.

When there are 2 cards out then the A drop is 52% successful versus the finesse 50%.
When there are 3 cards out then the A drop is 25.7% successful versus the finess 50%.
So the drop is only about half as successful when there are 3 cards out instead of 2, and no longer makes sense.
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### #8gszes

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Posted 2018-February-12, 08:24

The relative success of a situation depends on thinking about all of the possible lie of the cards (not always easy to calculate) and to go with the play that seems to have the highest chance of success. Note how Helene_T list ALL of the possible lie of the opponents cards to come up with the solution that the finesse is best. One thing to add, do not forget the bidding when making your decision. Lets say you are in 6s (your side has around 28 hcp) and east has opened 1h. That means east is a monster favorite to hold the spade King and taking the finesse becomes a huge probable loser while playing for the drop at least gives you a reasonable chance at making.
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### #9onaykk

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Posted 2018-February-12, 08:30

Thanks a lot
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### #10hrothgar

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Posted 2018-February-12, 08:32

I highly recommend a book titled "Bridge Odds for Practical Players"
Alderaan delenda est
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### #11pescetom

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Posted 2018-February-13, 07:36

hrothgar, on 2018-February-12, 08:32, said:

I highly recommend a book titled "Bridge Odds for Practical Players"

On it's way across the ocean, thanks
Together with "Card Play Technique or the Art of Being Lucky".
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