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Daily Quiz 3/28
Posted By: kruidenbuiltje In Response To: Daily Quiz 3/28 (Daily Quiz)
Date: Thursday, 5 April 2012, at 10:16 a.m.
Daily Quiz 28 march 2012
Number 1
It is clear that blue wins in this position, the question is how to maximize the gammons. After playing the safe 10/5 there are 2 white throws: 62,52 that leave two blots. That gives blue a chance of 10% max to pick up 2 blots. Since 4 blots on the 2-anchor gives an estimated gammon chance of 60%: 10% x 60% = 6% gammons. Then there are the throws D6,D5,65,42,32,43,D2 that leave 1 blot, that gives a max of 30% of 3 blots on the 2-anchor, this gives about 20% Gammons x 30% = 6% gammons.
So the safe variation picks up a maximum of 12 % gammons. But there are more creative variations here: 8/7 8/4 (creating 2 hitters) or even better 7/6 7/3 (creating 3 hitters). Knowing that closing out 1,2 or 3 checkers maximize the gammons to resp. 5%, 45%, 90% makes it clear that with this play blue has to pick up and close out a bit more than one checker on average. The fun is that all the above mentioned moves still leave as many blots, 65 is doing even better, and 51,53 and 54 leave blots as well. The only disadvantage is that checkers can more easily jump from the 2-anchor, with the gap on the bar-point. But I guess that the extra gammons will make up for that.
Answer: 7/6 7/3
Number 2
In this 4-holding position white has about 10% race-chance. Blue’s main problem is clearing the 10-point, he has 26 free pips, giving him 4 moves to do so. With 2 landing points there are 7/36 good clearing moves for blue the chance of leaving a shot is thus (29/36) ^ 4=(841/1296)^2 is about 65% ^2 = 42%. The hit is of a 16/36 magnitude, so: 16/36 x 42% = about 18%. There is one more thing to consider: are all of these hits winners? No! Because white only has 19 free pips, he will probably have his 6 point open by the time that blue leaves a hit, this means that a hit will make white a favourite, but not a winner. If we presume the take-point to be exactly on 25%, white should be a 83% favourite after hitting. My estimate is that he is more like a 2/3 favourite, so it must be a narrow pass.
Answer: DP
Number 3
I see 3 options here: 13/7 2x1 (risk 11/36), 7x1 2/1 (risk 6/36) and 13/6 (risk 13/36). I don’t think it is so very important to keep the bar-point, since the relative value has diminished in the light of the 4-anchor. The least risky option (7x1 2/1) has an extra advantage, it has a perfect diversification of the following numbers: 1,2,3,4 and 6 cover or safety the blot on the bar-point and 5’s escape a backchecker.
Answer: 7x1 2/1
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