Friday, December 7, 2012

4 player flush draw odds

Question:  In a four player game, how often will you make a flush when setting 2-4 flush cards in a hand?

With four players, we start seeing almost all of the deck in the late draws.  This means that there are some situations that are impossible, like having four flush cards in a hand with no other flush cards out and 1 draw to go.  In this case, there are 4 cards left to draw in the deck, which, even if they were all flush cards, would mean the deck had only 8 cards in that suit.  These situations are indicated in the table with "IMP".

There are also situations where the probability of getting a flush goes up as the draws progress, as with setting two cards and having no dead cards in any of the other three hands.  With this few dead cards out, the deck in the late draws is almost all flush cards.  Of course, these situations will be relatively rare.

Chance of completing a flush setting 4 flush cards, 4 player model 

dead cards
Draw 1
Draw 2
Draw 3
Draw 4
Draw 5
Draw 6
Draw 7
Last Draw
0
95.3%
95.7%
96.3%
97.0%
98.1%
99.5%
IMP
IMP
1
93.0%
93.4%
94.2%
94.8%
96.2%
98.2%
100.0%
IMP
2
89.7%
90.2%
90.7%
91.8%
93.0%
95.5%
100.0%
IMP
3
84.9%
85.7%
86.2%
87.0%
88.5%
90.8%
96.5%
IMP
4
78.7%
79.1%
80.0%
80.4%
81.8%
84.0%
89.3%
IMP
5
70.4%
70.6%
71.3%
71.9%
72.9%
74.3%
78.4%
100.0%
6
59.0%
59.3%
59.6%
60.3%
60.9%
61.7%
64.2%
75.1%
7
44.2%
44.3%
44.6%
44.8%
45.1%
45.3%
46.3%
50.1%

Chance of completing a flush setting 3 flush cards, 4 player model 

dead cards
Draw 1
Draw 2
Draw 3
Draw 4
Draw 5
Draw 6
Draw 7
Last Draw
0
80.7%
81.7%
83.0%
84.8%
88.0%
95.5%
IMP
IMP
1
74.2%
75.1%
76.1%
77.8%
80.9%
87.2%
IMP
IMP
2
66.8%
67.3%
68.1%
69.4%
71.7%
76.1%
100.0%
IMP
3
57.7%
58.2%
58.5%
59.7%
60.7%
63.5%
75.1%
IMP
4
47.4%
47.8%
48.0%
48.7%
49.0%
49.9%
53.8%
IMP
5
36.7%
36.6%
36.7%
36.5%
36.6%
36.3%
35.5%
IMP
6
25.3%
25.2%
25.2%
24.8%
24.4%
23.6%
21.5%
0.0%
7
14.7%
14.5%
14.5%
14.0%
13.4%
12.7%
10.8%
0.0%


Chance of completing a flush setting 2 cards, 4 player model

dead cards
Draw 1
Draw 2
Draw 3
Draw 4
Draw 5
Draw 6
Draw 7
Last Draw
0
57.4%
58.1%
58.9%
60.4%
63.3%
75.0%
IMP
IMP
1
48.8%
48.7%
49.3%
50.1%
51.0%
54.5%
IMP
IMP
2
39.6%
39.8%
39.6%
39.5%
39.2%
38.2%
IMP
IMP
3
30.9%
30.7%
30.2%
29.4%
28.1%
25.4%
0.0%
IMP
4
22.6%
22.3%
21.5%
20.7%
19.2%
16.0%
0.0%
IMP
5
15.0%
14.5%
13.9%
13.1%
11.8%
9.2%
0.0%
IMP
6
8.4%
8.3%
7.9%
7.4%
6.3%
4.5%
0.0%
IMP
7
4.0%
3.7%
3.6%
3.2%
2.7%
1.8%
0.0%
0.0%

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