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After much head scratching
I'm going for B. The 'first' answer is 25 per cent, but as that's half the chances, the final answer is B.
I think
Yeah but if
the answer's B that's only 25%....uuunngggh , make it stop
Assuming there's only one correct answer
it has to be 25%, surely?
I'm going to say that there is no correct answer.
The only conditions I can see for the answer to be correct are as follows: the percentage you select (point "A") must match the percentage chance you had of making such selection (point "B").
At present, points A and B line up as follows:
(i) Answer A/D: A = 25%, B = 50%
(ii) Answer B: A = 50%, b = 25%
(iii) Answer C: A = 60%, b = 25%
In order for there to be a correct answer you would need to either (i)substitute a figure of 33% for either option B or C and delete answer D (thereby giving a 33% chance of selecting such answer); or (ii) replace either option A or D with any other number (thereby giving you a 25% chance of selecting the remaining 25% answer.
I'm not an expert on probabilities, and I know that the mathematical laws in this area can sometimes run counter to intuition, but based on a quick look the above seems logical to me.
I await the poking of a million holes in this response.
There is a perfectly valid question and answer here.
But the answer isn't one of the "multiple choices" given, it's 0%.
We assume, from the format, that it's a multiple choice question, and it's not.
Sadly
I don't think 0% is a workable solution.
Of course, you're quite correct that we only assume this to be a multiple choice question with a fixed number of possible answers (4).
However, I would observe the following:
(a) if we're going to say that there are more than four answers we still need to cap the maximum number of possible answers or the use of a percentage makes no sense. If we're saying you can give any response you like to the question and you must select an answer at random then your prospects of selecting the correct answer (assuming there is one) would be one in infinity. I'm not sure you can express one in infinity as a percentage, so the question breaks down.
(b) more damagingly for the "0%" theory, I think it's logically inconsistent. Here's why: the theory relies on two propostions:
(i) 0% is an available answer (I.e we're not limited to the four multiple choices provided); and
(ii) 0% is the correct answer.
I think point (i) invalidates point (ii) because if 0% is in the pool of available answers you must have a greater than 0% chance of choosing it at random. Even if the pool includes an infinite number of options, your chances of randomly selecting 0% would still seem to be marginally above 0%.
Obviously, if point (i) is incorrect then 0% cannot be the solution as it is not an available option.
Put simply: if there's a 0% chance of finding/selecting the solution then you can't have found the solution.
The only way the question even really exists conceptually is if we accept that the solution must be a percentage equal to the chance of randomly selecting such percentage from the available response pool. Without taking serious liberties with the pool size (e.g imagining there are ten available responses and one of them is 10%) I don't believe that any such solution can be found. There is therefore no correct answer, regardless of whether the four original multiple choice options are definitive.
Hope that makes sense. Again, I'm approaching this from a logic (rather than a mathematical) perspective so it's quite possible I've overlooked some special property of the number 0 which makes this all work.
Good piece of logical
Good piece of logical semantics... There is a valid argument to say that for 0% to be the correct answer, the question should have asked: "If you chose one of the four answers below at random, what is the chance that you would be right?" One might also say that's splitting hairs... but then again this is ALL about splitting hairs!
Wiseman
This was doing the rounds on Twitter last week.
Check the Wiseman blog for a discussion of the answer.
http://richardwiseman.wordpress.com/2011/10/31/answer-to-the-friday-puzz...
This is like asking...
What letter did you select?
A) B
B) C
C) D
D) Wibble
My head hurts, too
I hate these kind of logic puzzles, for the same reason that I hate riddles, most poetry, and geometry. They all make me feel inadequate.
I don't want to figure it out. I just want someone to give it to me straight.
This
again
http://www.wordmagazine.co.uk/content/anyone-want-try-some-old-o-level-q...
(about half way down)
It's taken me all this time to get it out of my mind...
on the other thread you quoted
the question was paraphrased ... now i've seen it actually written down (see pic at top of this thread) it makes no sense whatsoever since there is no question
Eh?
.
OK, there are four answers, one of which is correct.
They are 'A', 'B', 'C' and 'D'.
Random selection gets you the right answer 25% of the time.
What's the issue?
It's not quite that simple
Despite the use of four letters, there are only really three answers (25%, 50% and 60%).
You therefore have a 33% chance of selecting any given answer, and since none of the answers is 33% it's not possible to be "correct".
Likewise, your chances of getting "25%" as the answer are 50%, rather than 25% (a two in four chance).
You can attempt to make the argument that probability is determined by the lettering of the options you're presented with, rather than with reference to the actual number of such options, but I would say you have a 0% chance of that particular suggestion being regarded as mathematically correct.
That's what I was thinking
Essentially, it's a one-in-three chance. Unless there is some way that A and D are in fact not the same.
Surely the answer is 0%
Most of the answers here are assuming an implication which isn't ACTUALLY in the question. The question doesn't state that one of the A-D options is right. It merely asks what the chances of being right are if you choose one of the options below. Which ever option you choose is wrong, therefore the answer is zero.
The trick depends upon us assuming
one of the answers is right - none of them is, but that doesn't prevent us from answering the question; the answer to the question is essentially the same as to the question "how much more blacker could this album sleeve be?"
In the old O Levels thread
I wondered if this was a paradox as 25%, 25% and 50% could be seen as equally correct or incorrect. If this is so, then what if the fourth solution was 75% not 60%? would that mean all four answers were correct ... to an extent?
Aha!
Now I understand what Eamonn O Donnell meant by a linguistic sleight of hand. You are trying to calculate the probability of a correct answer to that actual question on the board when, as Mr O D says, there is no question. All of my thinking was about a notional unknown multiple choice question where all we knew were the four possible answers.
Mr O Donnell has nailed it.
I think that's it
by just seeing four answers (and not what they are) you think 25%. When you see 25% presented twice, obviously there's two potentially correct answers to the question, and of course then 25+25 =50.
It's a trick question. Not quite 'Have you stopped beating up old ladies for no good reason?', but a trick question nonetheless...
But there IS a question.
And the answer is 0%.
Disagree
There is no question, so there can be no answer
the Solution
Take one sword , cleave blackboard in two , scratch backside , fart , turn on your heels , glower at anyone between you and the door , exit room AKA "Alexandrian solution".
Have you ever attempted
the Kobayashi Maru?
The first few minutes of this
should help:
Errrr
You have as much chance of being right as wrong. It's 50%.
If you choose from the "answers" given,
you have 0% chance of being right. There IS a question, and there IS a valid answer (no percent, none blacker). It's the format of the "multiple choice" answer that throws us. It's actually NOT a multiple choice question/answer! It's a very simple - or reasonably so - answer to a simple question' and we only feel cheated because we looked at the question the wrong way.
The question, then
Do you know the answer to this question? Is it
a) yes
b) no
Or:
What are the chances of getting the right answer to an unspecified question (ok, maybe any question) given these 4 possibilities, 2 of which are the same and none of which are necessarily correct?
All of which is thickened with the 2 25%s and 1 50% paradox.
I'm going to bed now. Really must get a proper job.
I like the way you think Burt and you are not wrong*
but consider this:
If, as you maintain, there is a question then
Either we are limited by the apparent multiple choice format of the question to the options a/b/c/d or we are not.
As you state none of a random selection from a, b, c or d can be correct. There is no possibility of a right answer choosing only among these four. So you say the answer is 0%.
But if you give 0% as your answer you acknowledge the question permits answers other than the a/b/c/d menu provided.
And if that's the case what's to stop me picking 0% as my random answer?
So now you have the paradox that if 0% is the right answer that means there is an answer - which in turn implies 0% must be wrong.
Paradoxes can be absolute contradictions but usually they are just apparent contradictions. In this case the contradiction is apparent and, I would suggest, is caused by the fact that the sentence may begin with an "If" and end with a question mark but it is not a question because it is meaningless.
*Okay I think you're wrong that there is a legitimate question being asked rather than a "linguistic sleight of hand" (E O D 2011) being performed.
This is the question:
This is the question:
"If you choose an answer to this question at random, what is the chance you will be correct?"
We are then presented with a "multiple choice answer" format which leads us (fools such as we be) to believe that one of them is correct.
BUT. The second appearance of 25% breaks the rules of a "multiple choice answer" set, and should alert us to the fact that something is amiss with our assumption. Answers within a multiple choice set have to be different to each other to enable a correct answer; two or more the same make a single choice "correct" answer impossible. This, then, in spite of its appearance, is NOT a multiple choice answer question. The suggested "answers" are as incorrect as the above analysis indicates.
So - the chances of us being correct in answering this question at random from the "suggested" values given will be zero.
Just because "zero" does not form part of the set of "answers" given does not invalidate the question - in fact, the opposite is true. It is because the "suggestions" are incorrect that a true answer to the question is not only possible but also unambiguous and definitive.
I think this is specious.
We are reasonably entitled to interpret this question as "If you choose an answer to this question at random, from the four choices below (a,b,c and d), what is the chance you will be correct?"
Answer: One in four.
Everything else is just pin head fairy counting. OOAA
Yep. I hear you Burt. I like it. But the problem is
the "question", being semantically inconsistent, is invalid.
Here's my question:
I'm holding a bag containing two snooker balls of different colours. If you put your hand in and select one at random what is the probability the ball you pull out will be
a) orange
b) purple
This question is formulated in the same way as the original question and here your answer of 0% would be correct.
The big difference is my question, having defined parameters, makes sense so your answer also makes sense.
The question in the OP ("If you choose an answer at random..") leaves open the possibility of choosing 0% or "No answer" as a random answer.
This is akin to you putting your hand in the bag and finding no ball there at all. At this point you might reach into your pocket and produce a piece of paper on which is written "There is no ball in the bag. The question is invalid".
The way I see it either
1) the question in its entirety makes sense and you must choose from a/b/c/d. (Not an option, obviously)
Or 2) you decide the multiple choice options cannot be correct but the question with them scratched out still makes sense in which case (because what we are choosing randomly is answers not snooker balls or cds or pieces of fruit) "No answer" is a valid random answer.
Or 3) the question doesn't make sense, which is where I stand.
It's thin ice, and I'm encouraged that eminentdan 1978 came up with the same answer as me independently.
And here's my question;
Why can you not choose from a,b,c or d?
If the question has been predicated on the fact that, say, 'a' is the correct answer, you have a 25% chance of choosing 'a' and being correct. The same applies if the question is predicated on any of the other choices being correct.
The fact that the values attached to the answer/letter choices might be repeated is irrelevant.
This is the only realistic practical conclusion, and all of the philosophising above is mere sophistication.
OOAA, but I remain to be convinced (without endless intellectualising bollocks).
I generally struggle
To avoid endless intellectualising bollocks, but let me have a go.
If the question was "What is your chance of randomly selecting response A?" then your logic would be sound.
But that's not the question. The question is "What is your chance of randomly selecting the correct answer?"
If the correct answer is "25%" then you clearly have a 2 in 4 (50%)chance of selecting it.
Hope that the above passes within the acceptable bollocks threshold.
But.
My point is that in any practical interpretation of reality, the chance of the phrase, "response A" and the phrase "the correct answer" being exactly the same thing in the terms of the question posed, is 25%.
Think of it this way
If all four options said "25%" would you still think that your chances of randomly selecting the correct answer were 1 in 4?
If so, I propose we put four pieces of paper in a hat, each marked with an X.
I will then wager you £100 that when I dip into the hat I will randomly select a piece of paper marked with an X.
According to your analysis, the odds will be in your favour.
'fraid not.
If you have four pieces of differently coloured paper, lets say, one Apricot, one Blue, one Carmine and one Daffodil yellow, I'll wager you £100 that you don't pick out my chosen colour with your first pick.
Oh, and you can write what you like on each piece of coloured paper; perhaps "25%" on two of them, "Discombobulate" on one, and "Massey Furguson FF 3660" on the last, it won't make a ha'peth of difference.
Not sure I follow that
So it doesn't matter what we write on the paper/which figures we ascribe to "a", "b", "c" and "d"?
If you take the question above and give the available answers:
a = 1%
b= 2%
c= 3%
d= Sausages
Your answer would still be 25%?
Are you basically saying that if you are given four possible answers and are told that only one of them is correct then you have a 25% chance of selecting it randomly?
If so, I wouldn't disagree, but the question doesn't state that one of the options is correct, and for "a" to be correct "d" would also need to be correct, wouldn't it?
That's not how exams work.
If 'a' is "Henry the Fifth" and 'd' is "Quatermass", it matters little if the question is 'Name the Vertigo band who had pterodactyls and skyscrapers on the cover of their debut album', or 'name a Shakespeare play that is centered around the Battle of Agincourt' if the examination board has decided that the answer is 'c' "The square root of minus one".
:)
Ah
So it's a case of "this is an exam situation, there must be a single correct answer, therefore it's a 25% chance if taken at random".
I have to say that, while I think it ignores several of the key features of the question above, I believe yours to be the best approach.
Why? Because in said exam situation, the kid who ticks "25%" and proceeds to spend their remaining allotted time answering questions that aren't designed to cause an aneurysm will dramatically out-perform the kid who spends 45 minutes explaining why there is no question/there is no answer/the answer is 0%/it's not really multiple choice (delete as appropriate).
Perhaps that's the lesson here.
Yep. Certainly a ferocious waste of exam time.
25% is no more right or wrong than any other answer so why not? Just make sure if the question arises outside the exam hall (In Paul Daniels' Bunco Booth, say) you don't put money on it...
Okay Vulpes, last time. As bollocks free as I can make it
Forget the percentages they are only there to trick you. Forget the fact that one of the answers appears twice this is also meant to cause confusion.
Imagine a question like this:
An unbiased 10p coin falls to the floor. What are the chances of randomly guessing which side is facing up. That is 50/50.
The answer is 50/50 because I have formulated a legitimate problem and, knowing the problem, you can calculate the odds of either side being face up.
In contrast
"If you choose an answer to this question at random, what is the chance the answer will be correct?"
provides us with no problem and therefore there is no method of calculating a probability a random answer can be correct.
0% is just an option from the universe of possible answers to an unasked question no more likely than 50%
We should say "Go on, I'm still waiting for the question".
If you try to say "There is no correct answer" you tie yourself in a logical knot (this bit is the intellectual bollocks) because if this answer is correct then it cannot be correct. It is an absurdity.
We have arrived at absurdity because we took the question seriously rather than treating it as a nasty piece of gibberish designed to trick us.
Next week: If God is all powerful can he make a rock so heavy he can't lift it?
Not sure I agree with the above
I think that there is a legitimate question in there.
It doesn't go to the extent of stating "If you select randomly from the four available options below", but the implication is clear and if the available options actually contained a correct answer you'd not think for a moment that the question actually intended you to consider all possible responses (which are presumably infinite in number).
Imagine, for instance, that the available answers were A: 25%, B: 50%, C: 75% and D: 100%.
You'd answer the question in 30 seconds flat.
The problem isn't with the question, it's with the available responses.
The only possible condition I can see for a correct answer is where the response and the percentage chance of selecting said response are equal.
None of the available responses meet this criteria, and therefore there is no answer unless we choose to reinterpret the question to expand the pool of available responses. Even then, you run into the issue of there being infinite possible responses once you go beyond the four offered.
I also don't agree that stating "There is no correct answer" ties you in a logical knot. How else are we supposed to explain that there is no logical answer to a question? How should be respond to the following for instance?
Which of the following four numbers is the sum of 3 x 5?
(a) 10
(b) 30
(c) 60
(d) 100
Clearly, we must be permitted to point out that a question and the available responses do not produce a logically consistent "correct" solution? All we're saying is that the question can't be answered on its own terms, not that there is no available response to it.
Last last last time before I go mad
Assuming by "Which of the four following numbers is the sum of 3 X 5?" you mean which of a, b, c or d is equal to 3 X 5 the answer is none of them. There is an correct answer to the stated problem of 3 X 5. It is 15. However you have not provided 15 in your menu of answers. Here I would assume a misprint rather than a deliberate trick. Either way the question is invalid.
The nonsense where the only correct answer is that there is no correct answer only arises because there is no question. It's pretty much proof of gibberish.
In order to have a real problem you must either have a question before
"If.." or after "..will be correct"
You may choose to respect the riddle by assuming there is a question "offscreen" to which, say, 50% might be the correct answer but without knowing the question there is no way of calculating the probability a random punt will be right. Here's £ 50. You can pick all of the numbers on the number line. The unseen question was "Who is Bart Simpson's dad?" The answer is Homer. You have made an infinite number of guesses and I am £50 richer.
Seriously Dude, it's a trick. Do not respect it.
Oh and Ivan was right
It's exactly the same as "Have you stopped beating your wife?" the problem lies 100% in the careful phrasing of the non-question.
It does not compute, as they used to say in the old movies
Still not convinced
While the question is, at minimum, poorly phrased, it's possible to make the whole thing make sense and generate a workable correct answer purely by changing option "d" to anything other than "25%".
The question therefore does compute, it's just that the available answers do not.
Apologies for being infuriating - I'm just trying to work out if I've missed something here. And I'm a sucker for logic puzzles.
Come on, then, if you think you're hard enough -
Get someone to hold your coat while I give Pete Seeger the kicking he so richly deserves.
Surely the answer is, as always,
David Bowie
So what is the correct answer?
Please.
further thoughts
"If you choose an answer to this question at random, what is the chance you will be correct."
What question? There is no question.
If you assume that it's asking for the answer to an unspecified question at random then the question could be anything (an infinite set of possibilities or ∞) and the answer would be 1/∞ which is close to zero but not actually zero.
But I still think there's no question there.
You forgot the ? at the end of the question.
:)
There is a question, but it's meaningless, and therefore without a sensible answer, unless you make the practical assumption that one of the proferred options is previously selected as the correct answer. Ergo, if there are four of them, and you pick one at random, you've a 25% chance of getting it right. All else is either deliberate semantically introduced mind-fuckery, or interpretative sophistry.
ah azzyoom nuzzink
an ah cen poot a ? question mairk anywharr ah lake, eet deurs neurt make ze sentaince a propair question, allez, salut maintenant
or in English
just because i walk into a room and bark 'What?' at the assembled throng doesn't make my utterance a meaningful question - even though it has a question mark at the end ...
I know the answer to this, it's...
( * )Y( * )
It's the answer to everything that confuses me.
As any fule kno
the answer is 42.