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Bridge Probabilities and Combinatorics



Bridge Probabilities and Statistics - Suit Distribution

What is the probability of getting a particular suit distribution?


Computer Program by Bill Butler


   Everyone is used to getting hands where the maximum number of cards in any one suit is 5 or less. Occasionally six, seven, or even longer suits show up. The table below shows the number of combinations and probability of getting all possible suit distributions. We assume the deck is completely randomized before the hands are dealt. In practice there are usually only 3 or 4 shuffles between hands in ordinary social bridge. This is not enough to completely randomize the cards when the input to the shuffle is tricks consisting of clumps of cards in the same suit. As a result, long suited "weird" hands show up more frequently than would otherwise be expected.

   The first column in the table below lists all possible suit length combinations (Each number is a suit length). The second column lists the total number of possible hands that exist for each suit distribution. These must add to the total combinations that exist for a Bridge hand which is: COMBIN( 52, 13) = 635,013,559,600. The probability of a given suit distribution is simply the Total Hands for this distribution divided by the total possible hands (635,013,559,600).

Distribution           Total Hands      Probability
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13, 0, 0, 0                      4      6.29908 E-12
12, 1, 0, 0                  2,028      3.19363 E-09
11, 2, 0, 0                 73,008      1.14971 E-07
11, 1, 1, 0                158,184      2.49103 E-07
10, 3, 0, 0                981,552      1.54572 E-06
10, 2, 1, 0              6,960,096      1.09605 E-05
10, 1, 1, 1              2,513,368      3.95798 E-06
 9, 4, 0, 0              6,134,700      9.66074 E-06
 9, 3, 1, 0             63,800,880      0.000100472
 9, 2, 2, 0             52,200,720      8.22041 E-05
 9, 2, 1, 1            113,101,560      0.000178109
 8, 5, 0, 0             19,876,428      3.13008 E-05
 8, 4, 1, 0            287,103,960      0.000452123
 8, 3, 2, 0            689,049,504      0.00108509
 8, 3, 1, 1            746,470,296      0.00117552
 8, 2, 2, 1          1,221,496,848      0.00192358
 7, 6, 0, 0             35,335,872      5.56459 E-05
 7, 5, 1, 0            689,049,504      0.00108509
 7, 4, 2, 0          2,296,831,680      0.00361698
 7, 4, 1, 1          2,488,234,320      0.0039184
 7, 3, 3, 0          1,684,343,232      0.00265245
 7, 3, 2, 1         11,943,524,736      0.0188083
 7, 2, 2, 2          3,257,324,928      0.00512954
 6, 6, 1, 0            459,366,336      0.000723396
 6, 5, 2, 0          4,134,297,024      0.00651056
 6, 5, 1, 1          4,478,821,776      0.00705311
 6, 4, 3, 0          8,421,716,160      0.0132623
 6, 4, 2, 1         29,858,811,840      0.0470207
 6, 3, 3, 1         21,896,462,016      0.0344819
 6, 3, 2, 2         35,830,574,208      0.0564249
 5, 5, 3, 0          5,684,658,408      0.00895203
 5, 5, 2, 1         20,154,697,992      0.0317390
 5, 4, 4, 0          7,895,358,900      0.0124334
 5, 4, 3, 1         82,111,732,560      0.129307
 5, 4, 2, 2         67,182,326,640      0.105797
 5, 3, 3, 2         98,534,079,072      0.155168
 4, 4, 4, 1         19,007,345,500      0.0299322
 4, 4, 3, 2        136,852,887,600      0.215512
 4, 3, 3, 3         66,905,856,160      0.105361
 Total             635,013,559,600      1.000000


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