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Riddle About Rabbits
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Platypus
Oct 3, 2018, 6:12:07 PM10/3/18
to
You are a naturalist, looking, in the local meadow, for a rare wild albino rabbit. Only 1 in 300 wild rabbits is an albino. The local meadow contains 301 wild rabbits, 1 of whom is an albino, the rest being normal.
You are very good at distinguishing rabbits as albino or not albino, even at a distance. When you spot a rabbit that is albino, you correctly identify it as albino 99% of the time, and misidentify it as normal 1% of the time. When you spot a normal rabbit, you correctly identify it as normal 99% of the time; and misidentify it as albino 1% of the time. Any confusion is cleared up after you actually catch the rabbit.
All the rabbits in the meadow are equally shy, and equally easy to spot. When you spot a rabbit, it has equal chances of being any one of the 301 rabbits.
You spot a rabbit in the meadow. You identify it as albino.
You catch the rabbit. What are the chances that it is a real albino? (A reasonably accurate approximation will be accepted as correct).
You are very good at distinguishing rabbits as albino or not albino, even at a distance. When you spot a rabbit that is albino, you correctly identify it as albino 99% of the time, and misidentify it as normal 1% of the time. When you spot a normal rabbit, you correctly identify it as normal 99% of the time; and misidentify it as albino 1% of the time. Any confusion is cleared up after you actually catch the rabbit.
All the rabbits in the meadow are equally shy, and equally easy to spot. When you spot a rabbit, it has equal chances of being any one of the 301 rabbits.
You spot a rabbit in the meadow. You identify it as albino.
You catch the rabbit. What are the chances that it is a real albino? (A reasonably accurate approximation will be accepted as correct).
Butterbumps@Home
Jan 21, 2019, 3:03:57 AM1/21/19
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torstai 4. lokakuuta 2018 1.12.07 UTC+3 Platypus kirjoitti:
> You are a naturalist, looking, in the local meadow, for a rare wild albino
> rabbit. Only 1 in 300 wild rabbits is an albino. The local meadow contains
> 301 wild rabbits, 1 of whom is an albino, the rest being normal.
There's something weird about this. Shouldn't there be 299 and 1?
> You are a naturalist, looking, in the local meadow, for a rare wild albino
> rabbit. Only 1 in 300 wild rabbits is an albino. The local meadow contains
> 301 wild rabbits, 1 of whom is an albino, the rest being normal.
> You spot a rabbit in the meadow. You identify it as albino.
>
> You catch the rabbit. What are the chances that it is a real albino? (A
> reasonably accurate approximation will be accepted as correct).
--
C@w
Platypus
Mar 1, 2019, 11:57:35 PM3/1/19
to
On Monday, January 21, 2019 at 3:03:57 AM UTC-5, Butterbumps@Home wrote:
> There's something weird about this. Shouldn't there be 299 and 1?
Not if you throw in an extra rabbit who has a 299 out of 300 chance of being normal, and is in fact normal. Specific information takes precedence over general odds. Anyway, it should not make a difference if there are 300 or 301 rabbits in total. Like I said, an approximately correct answer should be accepted.
> There's something weird about this. Shouldn't there be 299 and 1?
> No idea. Is there actually such thing, or are you playing "rabbit" terminology jokes here? I'm going to say there is a 0% chance it is the albino rabbit, but I have no idea why.
Butterbumps@Home
Mar 21, 2019, 5:41:01 AM3/21/19
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lauantai 2. maaliskuuta 2019 6.57.35 UTC+2 Platypus kirjoitti:
> > No idea. Is there actually such thing, or are you playing "rabbit"
> > terminology jokes here? I'm going to say there is a 0% chance it is the
> > albino rabbit, but I have no idea why.
>
> That is not the correct answer.
Oh well.
> > No idea. Is there actually such thing, or are you playing "rabbit"
> > terminology jokes here? I'm going to say there is a 0% chance it is the
> > albino rabbit, but I have no idea why.
>
> That is not the correct answer.
B@w
--
Sorry, that's about all I've got for the riddle unless you want to solve it.
Butterbumps@Home
Mar 21, 2019, 5:44:05 AM3/21/19
to
lauantai 2. maaliskuuta 2019 6.57.35 UTC+2 Platypus kirjoitti:
> > No idea. Is there actually such thing, or are you playing "rabbit"
> > terminology jokes here? I'm going to say there is a 0% chance it is the
> > albino rabbit, but I have no idea why.
>
> That is not the correct answer.
I mean seeing as how the riddle states explicitly that you identify it as albino and then catch that same ID'd rabbit, I wanted to say there's a 100% chance it's an albino. But that seemed too obvious.
> > terminology jokes here? I'm going to say there is a 0% chance it is the
> > albino rabbit, but I have no idea why.
>
> That is not the correct answer.
B@w
--
Now I'm out of guesses though.
Butterbumps@Home
Mar 21, 2019, 5:47:00 AM3/21/19
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torstai 21. maaliskuuta 2019 11.44.05 UTC+2 Butterbumps@Home kirjoitti:
> I mean seeing as how the riddle states explicitly that you identify it as
> albino and then catch that same ID'd rabbit, I wanted to say there's a 100%
> chance it's an albino. But that seemed too obvious.
Crud, I meant 99% based on the weird statistical likelihood thing, but whatever. I discounted that as the answer because this is a riddle, not a probability problem in a maths book, right?
> I mean seeing as how the riddle states explicitly that you identify it as
> albino and then catch that same ID'd rabbit, I wanted to say there's a 100%
> chance it's an albino. But that seemed too obvious.
B@w
--
And what does it have in its pocketses?
Platypus
Apr 5, 2019, 5:03:53 PM4/5/19
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The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99% likely to identify it correctly.
It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely to be correct. That is actually a different question.
And in this particular context, it makes a huge difference.
(I have no particular memory of encountering this in a math book. It's just a situation I run into now and then, which affects people's ability to accurately assess probabilities, when any particularly rare phenomenon is involved. They don't understand (for instance) why the nice-seeming, honest seeming, intelligent seeming old lady who claims to be 110 years old, and has no known reason to lie, is in fact probably lying, confused or otherwise wrong.
Platypus
Apr 6, 2019, 1:57:48 PM4/6/19
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Here's the answer
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The 99% accurate observer, when he sees what he thinks is an albino rabbit, is only (roughly) 25% likely to be right. This is easiest to see when we consider that, when he sees all 301 rabbits in the meadow at once, he is going to identify roughly 4 of them as albino, when in fact only 1 of them is albino.
This illustrates the principle that extraordinary claims require extraordinary proof. Most bigfoot sightings are in error, not necessarily because bigfoot does not exist (though I guess he probably doesn't) but rather because, even if he exists, he must be very rare.
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The 99% accurate observer, when he sees what he thinks is an albino rabbit, is only (roughly) 25% likely to be right. This is easiest to see when we consider that, when he sees all 301 rabbits in the meadow at once, he is going to identify roughly 4 of them as albino, when in fact only 1 of them is albino.
This illustrates the principle that extraordinary claims require extraordinary proof. Most bigfoot sightings are in error, not necessarily because bigfoot does not exist (though I guess he probably doesn't) but rather because, even if he exists, he must be very rare.
Butterbumps@Home
Apr 16, 2019, 7:50:19 AM4/16/19
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lauantai 6. huhtikuuta 2019 0.03.53 UTC+3 Platypus kirjoitti:
> The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99% likely
> to identify it correctly.
>
> It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely to be
> correct. That is actually a different question.
Actually it says "When you spot a rabbit that is albino, you correctly identify it as albino 99% of the time ... You spot a rabbit in the meadow. You identify it as albino."
> The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99% likely
> to identify it correctly.
>
> It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely to be
> correct. That is actually a different question.
So ... I call dubiousies on this riddle.
B@w
--
I do like the dissonance between seeing and identifying, and the fact that you should have incorrectly identified 3 rabbits in the field - but it wasn't written well.
Platypus
Apr 26, 2019, 1:47:45 PM4/26/19
to
On Tuesday, April 16, 2019 at 7:50:19 AM UTC-4, Butterbumps@Home wrote:
> lauantai 6. huhtikuuta 2019 0.03.53 UTC+3 Platypus kirjoitti:
>
> > The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99% likely
> > to identify it correctly.
> >
> > It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely to be
> > correct. That is actually a different question.
>
> Actually it says "When you spot a rabbit that is albino, you correctly identify it as albino 99% of the time ... You spot a rabbit in the meadow. You identify it as albino."
>
> So ... I call dubiousies on this riddle.
"You spot a rabbit that is albino" does not mean the same thing as "you spot a rabbit that you identify as albino". As you acknowledge below. So where is the dubiousness?
> lauantai 6. huhtikuuta 2019 0.03.53 UTC+3 Platypus kirjoitti:
>
> > The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99% likely
> > to identify it correctly.
> >
> > It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely to be
> > correct. That is actually a different question.
>
> Actually it says "When you spot a rabbit that is albino, you correctly identify it as albino 99% of the time ... You spot a rabbit in the meadow. You identify it as albino."
>
> So ... I call dubiousies on this riddle.
> I do like the dissonance between seeing and identifying, and the fact that
> you should have incorrectly identified 3 rabbits in the field - but it
> wasn't written well.
It puts you in the shoes of the naturalist, and precisely identifies the problem he faces. It also precisely identifies the circumstances under which he is 99% accurate.
Odds tend to change whenever new information is acquired. In this case, new information was acquired. You failed to take the new information into account. That's not the fault of the riddle.
You knew that the odds of seeing an albino are 1 in 301. That information was also supplied. Does that still apply when after you tentatively identify the rabbit as albino? Or does your tentative identification radically increase the chance that it is actually albino? It does.
So why should it be any different with the 99/100 odds, that the riddle also gave you? You have to combine those 2 pieces of information. You just can't pick one and ignore the other.
The new information alters the odds. The new odds are alot higher than 1 in 301, but alot lower than 99/100. The new odds are roughly 1 in 4.
Butterbumps@Home
May 16, 2019, 4:52:06 AM5/16/19
to
perjantai 26. huhtikuuta 2019 20.47.45 UTC+3 Platypus kirjoitti:
> > > The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99%
> > > likely to identify it correctly.
> > >
> > > It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely
> > > to be correct. That is actually a different question.
> >
> > Actually it says "When you spot a rabbit that is albino, you correctly
> > identify it as albino 99% of the time ... You spot a rabbit in the meadow.
> > You identify it as albino."
> >
> > So ... I call dubiousies on this riddle.
>
> "You spot a rabbit that is albino" does not mean the same thing as "you spot
> a rabbit that you identify as albino". As you acknowledge below. So where
> is the dubiousness?
Right, it rides on the very easy to misread or misinterpret difference between "spotting an albino rabbit and identifying it as such" and "spotting a rabbit and identifying it as albino".
> > > The given information says WHEN YOU SEE AN ALBINO RABBIT you are 99%
> > > likely to identify it correctly.
> > >
> > > It does NOT say WHEN YOU IDENTIFY A RABBIT AS ALBINO you are 99% likely
> > > to be correct. That is actually a different question.
> >
> > Actually it says "When you spot a rabbit that is albino, you correctly
> > identify it as albino 99% of the time ... You spot a rabbit in the meadow.
> > You identify it as albino."
> >
> > So ... I call dubiousies on this riddle.
>
> "You spot a rabbit that is albino" does not mean the same thing as "you spot
> a rabbit that you identify as albino". As you acknowledge below. So where
> is the dubiousness?
*The narrator* has identified the rabbit in the first case, and the narrator does so with 100% accuracy.
I call dubiousies because it's not a riddle, it's a lesson in linguistic accuracy and reading comprehension. Yes, some riddles are that as well, but they're also riddles.
> > I do like the dissonance between seeing and identifying, and the fact that
> > you should have incorrectly identified 3 rabbits in the field - but it
> > wasn't written well.
>
> How should it have been written?
To be a trick to reveal that people read lazily? Exactly as it was written I suppose.
> It puts you in the shoes of the naturalist, and precisely identifies the
> problem he faces. It also precisely identifies the circumstances under which
> he is 99% accurate.
>
> Odds tend to change whenever new information is acquired. In this case, new
> information was acquired. You failed to take the new information into
> account. That's not the fault of the riddle.
> You knew that the odds of seeing an albino are 1 in 301. That information
> was also supplied. Does that still apply when after you tentatively identify
> the rabbit as albino? Or does your tentative identification radically
> increase the chance that it is actually albino? It does.
>
> So why should it be any different with the 99/100 odds, that the riddle also
> gave you? You have to combine those 2 pieces of information. You just can't
> pick one and ignore the other.
>
> The new information alters the odds. The new odds are alot higher than 1 in
> 301, but alot lower than 99/100. The new odds are roughly 1 in 4.
B@w
--
I've just spotted a pointless argument in a field. I've got a 99% chance of being right about it.
Platypus
May 23, 2019, 1:20:48 AM5/23/19
to
To me, "riddle", "puzzle" and "conundrum" are all more or less synonyms. If you don't like the title "riddle about rabbits", then call it a "conundrum about conies". It changes nothing about the problem, when you actually read it.
The riddle (or conundrum) is not meant to be worded in a confusing manner. It is meant to be worded as clearly as possible. That's why I asked you how it could be worded better. You dodged the question, by merely repeating your accusation that I had deliberately worded the problem in an unnecessarily confusing manner.
Yes, the problem involves ideas that I know to be confusing. I presented a problem I know people tend to get confused about. Similar distinctions confuse people in real life situations. If you understand why 99% is the wrong answer, and (roughly) 25% is the right answer, you are also more likely to avoid many similar real life probability mistakes.
I presented the same problem, worded in an identical manner, in a chess forum. Some were confused by it. Some quickly understood it, and presented the right answer. Nobody, including you, has ever explained to me how it could be worded better.
The riddle (or conundrum) is not meant to be worded in a confusing manner. It is meant to be worded as clearly as possible. That's why I asked you how it could be worded better. You dodged the question, by merely repeating your accusation that I had deliberately worded the problem in an unnecessarily confusing manner.
Yes, the problem involves ideas that I know to be confusing. I presented a problem I know people tend to get confused about. Similar distinctions confuse people in real life situations. If you understand why 99% is the wrong answer, and (roughly) 25% is the right answer, you are also more likely to avoid many similar real life probability mistakes.
I presented the same problem, worded in an identical manner, in a chess forum. Some were confused by it. Some quickly understood it, and presented the right answer. Nobody, including you, has ever explained to me how it could be worded better.
Butterbumps@Home
May 23, 2019, 8:40:13 AM5/23/19
to
torstai 23. toukokuuta 2019 8.20.48 UTC+3 Platypus kirjoitti:
> I presented the same problem, worded in an identical manner, in a chess
> forum. Some were confused by it. Some quickly understood it, and presented
> the right answer. Nobody, including you, has ever explained to me how it
> could be worded better.
---
> I presented the same problem, worded in an identical manner, in a chess
> forum. Some were confused by it. Some quickly understood it, and presented
> the right answer. Nobody, including you, has ever explained to me how it
> could be worded better.
A meadow contains 301 rabbits: 1 albino, 300 normal.
When you see an albino rabbit, you correctly identify it 99 times out of a hundred.
When you see a normal rabbit, you correctly identify it 99 times out of a hundred.
You see a rabbit (colouration undefined) and identify it as albino.
What are the odds that it is in fact albino?
---
There. That is the information as properly distilled and expressed in the original "riddle". This phrasing makes it perfectly clear that according to your ability, out of a sample of 301 you will identify 3 or 4 rabbits as albino when there is in fact only 1 in the sample, which means that all things being equal, the one you have found in the example has a 1 in 3 or 4 chance of being correctly identified and therefore an albino.
The "riddle" was worded misleadingly. Which is fine, if you accept that that is the point of riddles. But it means this isn't a riddle, but a mathematical logic puzzle in the guise of a riddle. My mistake was coming at it like it was a riddle, which does not usually depend on mathematics to answer.
Which is also fine. But don't be coming at me like that.
B@w
--
Also I just posted about actual George RR Martin related stuff so you could hit that up if you care.
Platypus
May 23, 2019, 6:17:40 PM5/23/19
to
Your revision is much less clear.
You say what happens 99% of the time, but fail to say what happens the other 1% of the time. Maybe, in those other cases, the observer simply fails to make a determination. If that were the case, it would totally alter the answer. Without that extra information, there is no way to solve the riddle.
Also "identifies correctly" is less clear than "identifies as albino" or "identifies as normal". After all, if I identify an albino rabbit as a rabbit, I have, by some standards, identified it "correctly" (as a rabbit). This is perhaps less serious, as one might guess from context that "identifies correctly" means "identify as albino" (etc.) in this context.
You removed the line clarifying that all the rabbits are equally easy to spot, and equally likely to be spotted. I threw in this line because if the white rabbits are more conspicuous (as some might guess them to be), it might alter the answer to the question.
You fail to specify that the rabbit is spotted "in the meadow". The reader must assume this, in order to have any basis for identifying the rarity of albino rabbits. You also remove the general statement of rarity, which means the reader has nothing to fall back on if he does not assume the rabbit is spotted in the meadow referred to in your first sentence.
Of course, you could guess that the rabbit is in the meadow, by assuming that the first sentence is meant to be relevant to the riddle. But such assumptions can be dangerous in riddles ...:
As I was going to Saint Ives,
I met a man with seven wives.
Each wife had seven sacks;
Each sack had seven cats;
Each cat had seven kits;
Kits, cats, sacks, wives;
How many were going to Saint Ives?
But nothing of the sort occurs here. In all cases, the extra language, which you edited out, was put there to avoid confusion. Some of the language was there for a wee bit of flavor. Nothing was meant to cause confusion.
But I'm sorry that you did not care for my little riddle. Maybe you'll like the Saint Ives riddle better.
You say what happens 99% of the time, but fail to say what happens the other 1% of the time. Maybe, in those other cases, the observer simply fails to make a determination. If that were the case, it would totally alter the answer. Without that extra information, there is no way to solve the riddle.
Also "identifies correctly" is less clear than "identifies as albino" or "identifies as normal". After all, if I identify an albino rabbit as a rabbit, I have, by some standards, identified it "correctly" (as a rabbit). This is perhaps less serious, as one might guess from context that "identifies correctly" means "identify as albino" (etc.) in this context.
You removed the line clarifying that all the rabbits are equally easy to spot, and equally likely to be spotted. I threw in this line because if the white rabbits are more conspicuous (as some might guess them to be), it might alter the answer to the question.
You fail to specify that the rabbit is spotted "in the meadow". The reader must assume this, in order to have any basis for identifying the rarity of albino rabbits. You also remove the general statement of rarity, which means the reader has nothing to fall back on if he does not assume the rabbit is spotted in the meadow referred to in your first sentence.
Of course, you could guess that the rabbit is in the meadow, by assuming that the first sentence is meant to be relevant to the riddle. But such assumptions can be dangerous in riddles ...:
As I was going to Saint Ives,
I met a man with seven wives.
Each wife had seven sacks;
Each sack had seven cats;
Each cat had seven kits;
Kits, cats, sacks, wives;
How many were going to Saint Ives?
But nothing of the sort occurs here. In all cases, the extra language, which you edited out, was put there to avoid confusion. Some of the language was there for a wee bit of flavor. Nothing was meant to cause confusion.
But I'm sorry that you did not care for my little riddle. Maybe you'll like the Saint Ives riddle better.
Butterbumps@Home
May 24, 2019, 1:28:25 AM5/24/19
to
perjantai 24. toukokuuta 2019 1.17.40 UTC+3 Platypus kirjoitti:
> Your revision is much less clear.
Okay.
> Your revision is much less clear.
--
.
Butterbumps@Home
May 24, 2019, 1:36:08 AM5/24/19
to
perjantai 24. toukokuuta 2019 1.17.40 UTC+3 Platypus kirjoitti:
> As I was going to Saint Ives,
> I met a man with seven wives.
> Each wife had seven sacks;
> Each sack had seven cats;
> Each cat had seven kits;
> Kits, cats, sacks, wives;
> How many were going to Saint Ives?
And yes, see *this* is a riddle. As far as the information we're given, only you are going to Saint Ives. So at least one, although for all we know the man and his wives are also going.
> I met a man with seven wives.
> Each wife had seven sacks;
> Each sack had seven cats;
> Each cat had seven kits;
> Kits, cats, sacks, wives;
> How many were going to Saint Ives?
B@w
--
Or, as Samuel L Jackson says in Die Hard With a Vengeance, they're sitting on a fucking road, waiting on the how-the-Hell-should-I-know?
Titus G
May 26, 2019, 8:10:52 PM5/26/19
to
On 24/05/19 5:36 PM, Butterbumps@Home wrote:
> perjantai 24. toukokuuta 2019 1.17.40 UTC+3 Platypus kirjoitti:
>
>> As I was going to Saint Ives,
>> I met a man with seven wives.
>> Each wife had seven sacks;
>> Each sack had seven cats;
>> Each cat had seven kits;
>> Kits, cats, sacks, wives;
>> How many were going to Saint Ives?
>
> And yes, see *this* is a riddle. As far as the information we're given, only you are going to Saint Ives. So at least one, although for all we know the man and his wives are also going.
But if he is not a kit, a cat, a sack or a wife, then perhaps the answer
> perjantai 24. toukokuuta 2019 1.17.40 UTC+3 Platypus kirjoitti:
>
>> As I was going to Saint Ives,
>> I met a man with seven wives.
>> Each wife had seven sacks;
>> Each sack had seven cats;
>> Each cat had seven kits;
>> Kits, cats, sacks, wives;
>> How many were going to Saint Ives?
>
> And yes, see *this* is a riddle. As far as the information we're given, only you are going to Saint Ives. So at least one, although for all we know the man and his wives are also going.
is zero?
Even more confusing is the question of how many of the kittens were
correctly identified as albino.
Butterbumps@Home
May 27, 2019, 2:26:09 AM5/27/19
to
maanantai 27. toukokuuta 2019 3.10.52 UTC+3 Titus G kirjoitti:
> >> As I was going to Saint Ives,
> >> I met a man with seven wives.
> >> Each wife had seven sacks;
> >> Each sack had seven cats;
> >> Each cat had seven kits;
> >> Kits, cats, sacks, wives;
> >> How many were going to Saint Ives?
> >
> > And yes, see *this* is a riddle. As far as the information we're given,
> > only you are going to Saint Ives. So at least one, although for all we know
> > the man and his wives are also going.
>
> But if he is not a kit, a cat, a sack or a wife, then perhaps the answer
> is zero?
THIS CHANGES EVERYTHING
> >> As I was going to Saint Ives,
> >> I met a man with seven wives.
> >> Each wife had seven sacks;
> >> Each sack had seven cats;
> >> Each cat had seven kits;
> >> Kits, cats, sacks, wives;
> >> How many were going to Saint Ives?
> >
> > And yes, see *this* is a riddle. As far as the information we're given,
> > only you are going to Saint Ives. So at least one, although for all we know
> > the man and his wives are also going.
>
> But if he is not a kit, a cat, a sack or a wife, then perhaps the answer
> is zero?
> Even more confusing is the question of how many of the kittens were
> correctly identified as albino.
B@w
--
Actually the more I think about that guy with the wives and the cats, the more fascinated I am by their story. Sod St. Ives.
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