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Last Updated: Jan. 21, 2016

Bonus Spot Keno


Introduction





Bonus Spot Keno is a keno variant I noticed at the Rampart casino in Las Vegas on January 15, 2016. It plays the same way as conventional keno, except the player is paid more if the first number he chooses matches a ball draw.

Rules



  1. The player chooses 2 to 10 numbers from the range of 1 to 80.
  2. The first number chosen shall be marked as the "Bonus Spot," but the player may change one of his other choices to the Bonus Spot instead by touching the screen.
  3. The game shall draw 20 numbers at random from 1 to 80.
  4. The player shall be paid, in part, according to how many of his chosen numbers match the 20-ball draw by the game.
  5. If the Bonus Spot matches one of the 20 numbers drawn by the game, then the player will be paid from the Bonus Spot pay table. Otherwise, he will be paid from the Standard pay table, which pays equal or less for every win.


Analysis



The following pay tables are from the 5-cent game at the Rampart casino. The first is the Standard pay table and the second is the Bonus pay table.

Standard Pay Table

Catch Pick 2 Pick 3 Pick 4 Pick 5 Pick 6 Pick 7 Pick 8 Pick 9 Pick 10
0 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 0 0
2 15 1 1 0 0 0 0 0 0
3 47 3 2 2 0 0 0 0
4 100 10 2 1 1 0 0
5 820 50 18 10 5 3
6 1,500 240 70 25 14
7 7,500 1,000 250 90
8 10,000 4,000 800
9 10,000 4,000
10 10,000


Bonus Pay Table

Catch Pick 2 Pick 3 Pick 4 Pick 5 Pick 6 Pick 7 Pick 8 Pick 9 Pick 10
0 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 0 0
2 15 2 2 0 0 0 0 0 0
3 47 7 3 3 1 0 0 0
4 100 12 6 3 2 2 0
5 820 80 30 14 7 8
6 1,500 415 90 47 24
7 7,500 1,900 350 152
8 10,000 5,000 1,000
9 10,000 5,000
10 10,000


The next table shows the weighted average win for each number of picks and catches after considering the probability of matching the Bonus Spot.

Weighted Average Pay Table

Catch Pick 2 Pick 3 Pick 4 Pick 5 Pick 6 Pick 7 Pick 8 Pick 9 Pick 10
0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
2 15.00 1.67 1.50 0.00 0.00 0.00 0.00 0.00 0.00
3 47.00 6.00 2.60 2.50 0.43 0.00 0.00 0.00
4 100.00 11.60 4.67 2.14 1.50 0.89 0.00
5 820.00 75.00 26.57 12.50 6.11 5.50
6 1500.00 390.00 85.00 39.67 20.00
7 7500.00 1787.50 327.78 133.40
8 10000.00 4888.89 960.00
9 10000.00 4900.00
10 10000.00


The next table shows the probability of each combination of picks and catches.

Probability

Catch Pick 2 Pick 3 Pick 4 Pick 5 Pick 6 Pick 7 Pick 8 Pick 9 Pick 10
0 0.560127 0.416504 0.308321 0.227184 0.166602 0.121574 0.08826624 0.06374784 0.04579070
1 0.379747 0.430867 0.432732 0.405686 0.363495 0.315193 0.26646411 0.22066559 0.17957138
2 0.060127 0.138754 0.212635 0.270457 0.308321 0.326654 0.32814562 0.31642614 0.29525678
3 0.013875 0.043248 0.083935 0.129820 0.174993 0.21478623 0.24610922 0.26740237
4 0.003063 0.012092 0.028538 0.052191 0.08150370 0.11410518 0.14731890
5 0.000645 0.003096 0.008639 0.01830259 0.03260148 0.05142769
6 0.000129 0.000732 0.00236671 0.00571956 0.01147939
7 0.000024 0.00016046 0.00059168 0.00161114
8 0.00000435 0.00003259 0.00013542
9 0.00000072 0.00000612
10 0.00000011
Total 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.00000000 1.00000000 1.00000000


The final table shows the contribution to the return of each combination of picks and catches, which is the product of the probability and weighted average win tables above. The bottom row shows the overall return.

Return

Catch Pick 2 Pick 3 Pick 4 Pick 5 Pick 6 Pick 7 Pick 8 Pick 9 Pick 10
0 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
1 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
2 0.901899 0.231256 0.318953 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
3 0.652142 0.259487 0.218231 0.324549 0.074997 0.000000 0.000000 0.000000
4 0.306339 0.140271 0.133177 0.111838 0.122256 0.101427 0.000000
5 0.528838 0.232173 0.229537 0.228782 0.199231 0.282852
6 0.193477 0.285510 0.201171 0.226876 0.229588
7 0.183019 0.286814 0.193939 0.214926
8 0.043457 0.159341 0.130003
9 0.007243 0.029991
10 0.001122
Total 0.901899 0.883398 0.884780 0.887341 0.883376 0.884901 0.882479 0.888057 0.888483


The best odds, based on the Rampart 5-cent pay tables, is on the pick-2 at 90.19%.