#statistics problem with dice

1 messages · Page 1 of 1 (latest)

half crane
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Hannah finds two dice in the attic with a rather peculiar feature: they are not standard dice (which have every natural number between 1 and 6 exactly once), but on both there are six
certain (not necessarily different) non-zero natural numbers. Hannah notes that the probability distribution
the sum of the eyes of both dice is exactly the same as that of two standard dice.
For example, the probability of rolling a sum of 12 pips is equal to 1 . in both cases
36 .
What are all the possible pairs of dice that fit the description above? List them all and clearly explain why there cannot be others.

crude plinth
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yeah i know, but i dont wanna be like the other students, they dont know programming
It's not a matter of programming or not, gotta understand the subject first

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Which goes with probably doing it on paper first, before code

half crane
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k

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its not normal math class bro

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its like a challenge

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that you do with smart kids

placid fog
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You aren't going to be able to solve this by getting every combination and checking which ones meet the criteria

half crane
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so i cant really understand this

placid fog
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that's too many values

half crane
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it wouldve been cool tho

placid fog
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you have to actually find ways to reduce the sample size

placid fog
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Meaning you'll have to do the math to know which heuristics to apply to your program

half crane
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agreed

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so

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how

placid fog
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I'm not actually sure

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I'd have to think about this for a while

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this is a difficult problem actually

half crane
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ofc it is

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but the thing is, my code would work

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theoretically

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ping me if you found anything

placid fog
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I ran a different calculator that can handle bigger numbers. The number of combinations of two different dice containing all values 1 to 11 randomly is 3.2e7. That means there are a total number of possible rolls of about 1.03e15, which would take 935 terrabytes to store

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The "Generate, Map, Filter, Reduce" pattern isn't going to work here. I think this is more puzzle than math

half crane
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damn

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soo, programming isnt going to work either

placid fog
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I'm going to think about this while I get lunch. There's probably a way to reduce it

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My gut instinct is that it's a trick question and the answer is literally just two dice of [1,2,3,4,5,6]

half crane
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theres one solution

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but for the math thing you need to find why

placid fog
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Okay. So you need two dice with non standard numbers that nonetheless produce an identical probability curve as 2d6, right? That'd means that you'd need two dice whose expected values sum up to 7. So when checking your dice, you could filter the second list of dice to ones that have an expected value equal to 7-this die average

half crane
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what is 2d6

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where does it say it has to sum up to 7

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i dont get that part

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@placid fog

placid fog
half crane
placid fog
placid fog
half crane
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???????

placid fog
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The most common number to roll on 2d6 is 7. If you have a different set of dice with the same probability breakdown, that means the most common number to roll on them must also be 7. That would be the sum of the average roll of both dice

half crane