Friday, July 29, 2011

Percentage Change after Card Played 2

Calculation of percentage like previous article will change if cards have been played. Taking example and you of partner have 8 card sheets while holded card opponent only 5 cards. Hereinafter your first round play this suit and both each opponent join in. So, nowadays opportunity to get distribution 3-2 high because percentage division 5-0 has been eliminated.

Taking example you have to finish contract 3NT like following:

               West            East
                       ♠965            AK7
                       ♥73              AQ2
                       ♦J83             A1092
                       ♣AK853        764

You accept J lead of 3NT contract this. How do you play this deal? After opponent of lead J, you have owned 7 sure tricks. New player learn Percentage Play will chosen diamond finesse double to fulfill contract because owning opportunity 76%, whereas if hoping club of suit divided 3-2 only have opportunity 68%. So game which they do by playing club up at desk, if both opponent follow, hereinafter play d8, West win K and then play at suit heart. After winning with heart suit, you play club of suit again up at desk and continue by playing at J which unhappily re-won by West with Q and hereinafter cash three tricks again to abort your contract.

What wrong by playing at like above? Opportunity of club divided 3-2 (it) is true only 68%, but this first opportunity before played other cards. Moment first trick both opponent follow, hence probability of division card change, Nowadays opportunity 5-0 have been negated, and so it is with opportunity 4-1 (Club singleton 10, J, or Q) By eliminating some the possibility above hence opportunity of division 3-2 will increase until more than 78% but practically this opportunity according to tired Hugh Kelsey almost 90% because near enough impossible if West hold QJ102 not play one of the honor card when South play at up at dummy. Thereby, way of real correct in finishing this contract is; time play club and both opponent follow with small club by playing small club again both hand. To be more sharpness again, let us calculate percentage of division of card following.

Possibility of card distribution residing in on-hand fight against after playing club suit first round, taking example West play East and 2 play 9:

Do there still the way of other which have higher level opportunity from way of playing at like above? If us pay attention carefully, hence opportunity of division of card 3-2 owning 6 from 8 equivalent or existing possibility by 75%. When playing club up at dummy  second round, and take example West follow with 10, hence opportunity of division of card distribution which possible on the condition above is ( considering West have showed and 10 of 2 while East of 9).

Such as those which you see list above, in this case only owning one opportunity of division of card divided 4-1 from 4 existing possibility or 25%, its meaning opportunity of card residing in on-hand fight against and divided 3-2 is 75%.

If you wish more is deepening Lesson about percentage play of more complete, you earn reading it in book: “Bridge Odds for Practical Player“ by Hugh Kelsey. And as practice you please play deal following:

West            East
A54            QJ76
AK1092       65
93              AK
842            AK763

Without a hitch fight against, you succeed game bidding 3NT. West start lead with Q, how do you plan this game? Try to look for percentage play at owning highest percentage level!

Useful hopefully, and safe play at!

Translate from Magazine Bridge Indonesia, Percentage Change, by: Syahrial Ali, 3/07

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