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February 2024 - Challenge

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This problem is based on a suggestion by Frank Mayer - thanks Frank!


Alice and Bob play the following weird dice game using a standard set of 6 D&D dice, i.e., dice with values


1,\ldots,4

1,\ldots,6

1,\ldots,8

0,\ldots,9

1,\ldots,12

1,\ldots,20

At each round, they throw the dice and sum their values. All six dice need to be rolled once each round, and it doesn’t matter who rolls the dice. What matters in deciding who wins is the sum.


Alice wins if the result is a prime number, and Bob wins if the result is a nonprime even number. Otherwise, the result of the round is a draw.


The winner of the game is the first player to reach N consecutive wins.


Your goal: For N=13, find the probability that Alice wins the game.

A Bonus "*" will be given for finding the probability that Alice wins given that N=300 but the rules have changed and Bob now wins if the result is a nonprime odd number.


We will post the names of those who submit a correct, original solution! If you don't want your name posted then please include such a statement in your submission!

We invite visitors to our website to submit an elegant solution. Send your submission to the ponder@il.ibm.com.

If you have any problems you think we might enjoy, please send them in. All replies should be sent to: ponder@il.ibm.com

 

Challenge: 01/02/2024 @ 10:40 AM EST
Solution: 05/03/2024 @ 13:15 PM EST
List Updated: 11/03/2024 @ 09:30 AM EST

*Lazar Ilic(1/2/2024 4:59 PM IDT)
Lorenz Reichel(1/2/2024 5:07 PM IDT)
*Andrew Gauld(1/2/2024 8:49 PM IDT)
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Blaine Hill(2/2/2024 1:11 AM IDT)
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*Sanandan Swaminathan(2/2/2024 4:01 AM IDT)
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Richard Gosiorovsky(2/2/2024 1:23 PM IDT)
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Shelby Doolittle(4/2/2024 7:40 AM IDT)
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Kang Jin Cho(9/2/2024 8:26 PM IDT)
Paul Lupascu(9/2/2024 8:31 PM IDT)
*Dominik Reichl(9/2/2024 11:17 PM IDT)
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Gary M. Gerken(11/2/2024 4:57 AM IDT)
*David Greer(11/2/2024 2:21 PM IDT)
Frédéric Bossens(11/2/2024 5:38 PM IDT)
Stefan Wirth(11/2/2024 6:01 PM IDT)
Michael Branicky(11/2/2024 9:06 PM IDT)
*Nadav Rubinstein & Eden Saig(11/2/2024 9:26 PM IDT)
Evan Semet(12/2/2024 8:18 AM IDT)
Julien Vincent Pradier(12/2/2024 12:48 PM IDT)
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Pavel Stoimenov(19/2/2024 7:08 PM IDT)
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