Morg
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November 25th, 2021 at 2:15:33 PM permalink
Sort of an odd (and quite specific) question.

On a roll of 9 dice (d6), which are the probabilities of getting:
- three 3 of a kind (xxxyyyzzz configuration)
- at least 4 of a kind?


Many thanks to whoever could help
Dieter
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November 25th, 2021 at 3:57:53 PM permalink
Welcome to the forum.

To clarify, you're asking about a single roll of each die? (Possibly all at once)
May the cards fall in your favor.
Morg
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November 25th, 2021 at 4:06:11 PM permalink
Hi Dieter, thanks!

That's correct, a single roll of the 9 dice at once.
Dieter
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November 25th, 2021 at 4:46:15 PM permalink
... and you don't care what x y and z are, just that they're different?
May the cards fall in your favor.
Dieter
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November 25th, 2021 at 4:59:14 PM permalink
I'm going to have to recuse myself from math until at least Saturday, I'm afraid.

The effects of turkey overdose and liquid holiday cheer are doing a tapdance on my mind.
May the cards fall in your favor.
Ace2
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November 25th, 2021 at 5:26:15 PM permalink
Quote: Morg

Sort of an odd (and quite specific) question.

On a roll of 9 dice (d6), which are the probabilities of getting:
- three 3 of a kind (xxxyyyzzz configuration)
- at least 4 of a kind?


Many thanks to whoever could help
link to original post

For 3 of a kind in xxxyyyzzz format there should be a 20 * 84 * 20 / 6^9 chance
It’s all about making that GTA
Morg
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November 26th, 2021 at 1:55:34 AM permalink
Quote: Ace2

Quote: Morg

Sort of an odd (and quite specific) question.

On a roll of 9 dice (d6), which are the probabilities of getting:
- three 3 of a kind (xxxyyyzzz configuration)
- at least 4 of a kind?


Many thanks to whoever could help
link to original post

For 3 of a kind in xxxyyyzzz format there should be a 20 * 84 * 20 / 6^9 chance
link to original post



Many thanks Ace2!
Could you guide me through the resolution?
Morg
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November 26th, 2021 at 1:56:22 AM permalink
Quote: Dieter

I'm going to have to recuse myself from math until at least Saturday, I'm afraid.

The effects of turkey overdose and liquid holiday cheer are doing a tapdance on my mind.
link to original post



No worries at all of course, many thanks for looking into this!

I hope you had a wonderful Thanksgiving! :)
Ace2
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November 26th, 2021 at 8:18:07 AM permalink
20 ways to chose 3 numbers from 6 times 84 ways to place first triple among 9 places, times 20 ways to place second triple among 6 places. Divide by 6^9 total permutations

Assuming this is correct. But this is the method of counting valid permutations
It’s all about making that GTA
teliot
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November 26th, 2021 at 8:38:51 AM permalink
Quote: Ace2

20 ways to chose 3 numbers from 6 times 84 ways to place first triple among 9 places, times 20 ways to place second triple among 6 places. Divide by 6^9 total permutations

Assuming this is correct. But this is the method of counting valid permutations
link to original post

Verified. This is correct. The answer for xxxyyyzzz is 0.003334.

The answer for xxxxabcde is 0.284003
Last edited by: teliot on Nov 26, 2021
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ThatDonGuy
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November 26th, 2021 at 8:44:03 AM permalink
Quote: teliot

Quote: Ace2

20 ways to chose 3 numbers from 6 times 84 ways to place first triple among 9 places, times 20 ways to place second triple among 6 places. Divide by 6^9 total permutations

Assuming this is correct. But this is the method of counting valid permutations
link to original post

Where are you making sure that x, y & z are different?
link to original post


"20 ways to choose 3 numbers from 6" refers to the three different numbers.
There are C(9,6) = 84 ways to place the lowest of the three numbers among the nine dice, and C(6,3) = 20 ways to place the second of the three numbers among the remaining six dice.
Ace2
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November 26th, 2021 at 9:17:07 AM permalink
Quote: Morg

Sort of an odd (and quite specific) question.

On a roll of 9 dice (d6), which are the probabilities of getting:
- three 3 of a kind (xxxyyyzzz configuration)
- at least 4 of a kind?


Many thanks to whoever could help
link to original post

The calculation for “at least 4 of a kind” requires many more steps since you must consider the following possible combinations.

AAAAAAAAA
AAAAAAAAB
AAAAAAABB
AAAAAAABC
AAAAAABBB
AAAAAABBC
AAAAAABCD
AAAAABBBB
AAAAABBBC
AAAAABBCC
AAAAABBCD
AAAAABCDE
AAAABBBBC
AAAABBBCC
AAAABBBCD
AAAABBCCD
AAAABBCDE
AAAABCDEF

Calculating them all would be good practice for someone trying to improve their combinatorial skills
It’s all about making that GTA
teliot
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November 26th, 2021 at 11:04:07 AM permalink
Quote: ThatDonGuy

Quote: teliot

Quote: Ace2

20 ways to chose 3 numbers from 6 times 84 ways to place first triple among 9 places, times 20 ways to place second triple among 6 places. Divide by 6^9 total permutations

Assuming this is correct. But this is the method of counting valid permutations
link to original post

Where are you making sure that x, y & z are different?
link to original post


"20 ways to choose 3 numbers from 6" refers to the three different numbers.
There are C(9,6) = 84 ways to place the lowest of the three numbers among the nine dice, and C(6,3) = 20 ways to place the second of the three numbers among the remaining six dice.
link to original post

Yep -- I was just thinking about it differently. But concur, hence edited my OP.
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Ace2
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November 26th, 2021 at 11:32:02 AM permalink
Quote: Ace2

Quote: Morg

Sort of an odd (and quite specific) question.

On a roll of 9 dice (d6), which are the probabilities of getting:
- three 3 of a kind (xxxyyyzzz configuration)
- at least 4 of a kind?


Many thanks to whoever could help
link to original post

The calculation for “at least 4 of a kind” requires many more steps since you must consider the following possible combinations.

AAAAAAAAA
AAAAAAAAB
AAAAAAABB
AAAAAAABC
AAAAAABBB
AAAAAABBC
AAAAAABCD
AAAAABBBB
AAAAABBBC
AAAAABBCC
AAAAABBCD
AAAAABCDE
AAAABBBBC
AAAABBBCC
AAAABBBCD
AAAABBCCD
AAAABBCDE
AAAABCDEF

Calculating them all would be good practice for someone trying to improve their combinatorial skills
link to original post

On second thought, there’s a more efficient way to calculate this using inclusion-exclusion, much easier than calculating all the possible permutations listed above

For any individual number, there’s a 483,946 / 6^9 =~ 4.8021% chance it will appear four or more times in nine rolls. This is easily calculated by subtracting the ways of getting 0-3 appearances of the individual number from 6^9 possibilities

6 * 4.8021% would be a 28.8129% chance of getting four or more of any of the six possible numbers. But that double counts instances where two numbers have hit four or more times .

It’s easy to calculate there are 2,772 ways in 6^9 =~ 0.02751% chance of rolling two numbers four or more times. That times c(6.2) ways to choose the two numbers is 0.4126%. Be careful with this step…there 2,772 ways to roll two numbers including the one that’s already been selected (not any two)

28.8129% - 0.4126% = 28.4003% chance of rolling at least one 4-of-a-kind with nine dice
Last edited by: Ace2 on Nov 26, 2021
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Morg
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November 28th, 2021 at 9:03:26 AM permalink
Many thanks to all the kind souls that jumped in with a reply!
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