Look, you can’t complain about this after giving us so many scenarios involving N locked chests and M unlabeled keys.

https://explainxkcd.com/3015/

  • Ostrakon@lemmy.world
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    9 个月前

    You have a 1 in 2 chance of pulling a cursed arrow the first time.

    If you pulled a cursed arrow the first time, the second arrow has a 4 in 9 chance to be cursed. Otherwise, it’s 5 in 9.

    Personally I’d have resolved this as a single d10 once, and rerolled a 10 on the second arrow. I haven’t done the math to know if 3d6+1d4 <16 yields the same probability though.

    • NuXCOM_90Percent@lemmy.zip
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      9 个月前

      Its xkcd so I assume Randall et al did the math.

      From a play session perspective? If the GM is that good that they can mental math it, I would much rather be given one roll than a series of rolls. Ask anyone about their horror stories about grappling in 3e about how much that kills the game flow.

      Also: The verbiage is ambiguous (less so if you have the context of how many attacks per round a player has and what feat they are using) but I think you can represent “I grabbed two at once” and “I grabbed one and then one” with a binomial coefficient. Been more than a minute but poking chatgpt to remember the notation (nCk) and it is likely representable as (5C2)/(10C2) which is approximately 22.2%.

      As for the dice? I forget if the type of die meaningfully impacts this but 3d6+1d4=4-22. Whether a 16 maps to that 22.2% range is beyond my brain right now as this comment was mostly because I forgot the difference between nCk and nPk and felt like googling that.

      • godot@lemmy.world
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        9 个月前

        The type of dice used can meaningfully impact this. The chance of a 2 or 12 rolling 2d6 is 1/36, the chance rolling 1d8+1d4 is 1/32. The chance of rolling 7 on 2d6, the most common result, is 1/6. The chance of rolling a 5, 6, 7, 8, or 9 on a 1d8+1d4, all equally likely, is 1/8 each.

        Unlike you I can’t begin to remember the elegant way to find this. I also assume Randall would have it at least close to right.

        • AEsheron@lemmy.world
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          9 个月前

          Anydice.com can handle this stuff easily. As already pointed out in another comment, it does perfectly match. What it will not tell you is if you grabbed one or 2 arrows, though presumably a roll of 1-x could be used to say you got one, and x+1-15 means you got two.

    • superkret@feddit.org
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      9 个月前

      I dm Call of Cthulhu, so simply roll a luck check.
      The chance doesn’t follow maths, it follows the whims of That Which We Do Not See.
      And Randall has pushed his luck with them too far already.

      • ggppjj@lemmy.world
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        9 个月前

        I was gonna say, sounds like a great use-case for quantum statistics. Until the roll, each arrow is in a superposition where it can be said to be simultaneously cursed and normal. Luck check for each shot until all of either are fully gone.

    • [email protected]@sh.itjust.works
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      9 个月前

      Yeah, d10 (1-5 cursed, 6-10 normal), then repeat with 1 or 10 being a reroll. I’m curious what the intent of the character was, whether they’re looking for a simple answer or something contrived like the DM’s answer.