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Author Topic: Online dice probability calculator  (Read 7627 times)

ZicherCZ

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Online dice probability calculator
« on: September 20, 2013, 05:21 »

Now there's something I've been trying to find for quite some time - a calculator to which you can input a dice notation and the calculator will display the chance of the roll being higher or lower than a certain result.
For example, what's the chance of killing a demon with one BFG shot?
Now we know that a BFG is 10d6 damage, demon has 2 armor and 25 HP, so what's the probability of 10d6 >= 27?

I found the calculator here at anydice.com. I thought about sharing this with the rest of us here.

By the way, the probability of the example is over 94% :).
« Last Edit: September 20, 2013, 05:24 by ZicherCZ »
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thelaptop

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Re: Online dice probability calculator
« Reply #1 on: September 20, 2013, 07:59 »

Um.  By Law of Large Numbers, as the number of dice and sides go up (xdy), the distribution tends towards a normal distribution with μ = xE[dy] ~ x (1+y)/2, and σ² = Var[xdy], with an abuse of notation.

So your question can be recast into a "simple" look up on the normal distribution.

>.<

But the site is still cool.  Heheheheh...
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slave

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Re: Online dice probability calculator
« Reply #2 on: September 20, 2013, 08:28 »

I have used Wolfram Alpha for calculating these probabilities. The site you used is better for that purpose though.

Quote
For example, what's the chance of killing a demon with one BFG shot?
Now we know that a BFG is 10d6 damage, demon has 2 armor and 25 HP, so what's the probability of 10d6 >= 27?

Also, you probably know that, but the BFG deals plasma damage, which means that you should calculate the probability for 10d6 >= 26, since the effect of armor is halved.
« Last Edit: September 20, 2013, 08:34 by slave »
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emulord

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Re: Online dice probability calculator
« Reply #3 on: September 20, 2013, 12:34 »

This could be VERY useful for determining how many levels of Brute to take before taking other skills in a Angel of Berzerk run
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ZicherCZ

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Re: Online dice probability calculator
« Reply #4 on: September 21, 2013, 02:00 »

Thelaptop, that was a sample question. In fact, my motivation to find a site like this dates back to the time when WIKICOMP was still active. Plus, I was not asking for an average nor standard deviation ;).

Also, you probably know that, but the BFG deals plasma damage, which means that you should calculate the probability for 10d6 >= 26, since the effect of armor is halved.
Oops, you caught me here. Even as a sample question, it should have been a correct question.
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ParaSait

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Re: Online dice probability calculator
« Reply #5 on: September 21, 2013, 08:21 »

Um.  By Law of Large Numbers, as the number of dice and sides go up (xdy), the distribution tends towards a normal distribution with μ = xE[dy] ~ x (1+y)/2, and σ² = Var[xdy], with an abuse of notation.

So your question can be recast into a "simple" look up on the normal distribution.

>.<

But the site is still cool.  Heheheheh...
Maybe one could keep that method for in case someone is looking. Then one can show off what a cool math geek he is. :P
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