Monday, October 31, 2011

I really liked this one...

I answer lots of questions about Oracle.  Many of them are ambiguous, unclear, not fully specified, hard to follow.  It is like unraveling a puzzle sometimes (ok, most of the times...)

That is why I found this question to be really amusing - especially after reading the comments.  Lots of disagreement as to the meaning of the question!

So, what do you think the answer is... I'll post what I think after I see some feedback.  It is a very very interesting question.

And it also points to why I think the answer to all questions is mostly "Why" or "It depends".  We usually need a lot more information to answer what might appear to be simple questions.

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37 Comments:

Anonymous Oratabler said....

Very interesting question.

My take: Depends on *what* the correct answer is.

If the expected answer is 50% or 60%, the chance of being correct when making a random choice is 25%.
If the expected answer is 25%, the chance is 50%.

Mon Oct 31, 02:55:00 PM EDT  

Blogger llanas said....

The chance is 25%

Because the chance to choose correct answer to a question of four possible, we know that is 25%, and there are two anwsers with that label, so there is a chance of 50% to select correct answer. And that label is b) just one of four, so 25% ;)

Regards

Mon Oct 31, 03:00:00 PM EDT  

Blogger Bora said....

x1=25%, x2=50%, x3=60%
p(x1)=.50, p(x2)=.25, p(x3)=.25
p(x1 is correct)=p(x2 is correct)=p(x3 is correct) = p(c)= 1/3
The chance that you can pick the correct answer is
p(x1).p(c)+p(x2).p(c)+ p(x3).p(c) = p(c) (p(x1)+p(x2)+p(x3)) = 1/3 . 1 = 1/3 = .3333333333

Mon Oct 31, 03:54:00 PM EDT  

Blogger DrDaMour said....

Who says that any of the options are right in the first place? You can't just assume there's is a correct answer.

Mon Oct 31, 04:54:00 PM EDT  

Blogger jvh said....

0% because none of the answers are correct.

Mon Oct 31, 06:06:00 PM EDT  

Blogger Joel Garry said....

ADD

word: twwad

Mon Oct 31, 06:54:00 PM EDT  

Blogger zaks said....

prcedure thinking as
begin
loop
thinking; --forever
end loop;
end;

Mon Oct 31, 08:23:00 PM EDT  

Blogger zaks said....

This comment has been removed by the author.

Mon Oct 31, 08:24:00 PM EDT  

Blogger zaks said....

prcedure thinking call itself without stop condition make loop forever !
as sql speeking it seem like a DEADLOCK !!

Mon Oct 31, 08:48:00 PM EDT  

Blogger Ditto said....

To me, this is no different than the typical paradox statements such as:

"This statement is false."

I consider it a paradox :)
No answer.

Thought process on getting there:
Base chance of correct answer with 4 possibilites: 1/4 = 25 %.
There are 2 answers of 25%, therefore the chance of picking 25% is 2/4 = 50%.
oops, chance of picking 50%: 1/4 = 25%.
hmm, we've been here before.
Paradox.

Mon Oct 31, 09:39:00 PM EDT  

Blogger Mandrake said....

This comment has been removed by the author.

Mon Oct 31, 11:40:00 PM EDT  

Blogger Mandrake said....

25%. Since I am picking the answer at random, the probability of me being right is 0.25

Mon Oct 31, 11:42:00 PM EDT  

Anonymous Anonymous said....

B) 50%.

Since I'd be choosing either a or d, I'll have a 50% chance of being right.

Mon Oct 31, 11:54:00 PM EDT  

Anonymous Anonymous said....

I must ask my friend, the liar.

Tue Nov 01, 05:40:00 AM EDT  

Blogger Stew Ashton said....

When you choose at random, you choose "from" something. What are we choosing from: the set A,B,C,D or the set 25%,50%,60% or something else?

The various comments assume one or the other of those choices.

You could even "make" 50% the right answer by assuming the choices are 25%,50%,50%,60%. Indeed, by varying the assumptions you could "make" each answer right or wrong.

Tue Nov 01, 05:43:00 AM EDT  

Anonymous Bix- Ireland said....

Oracle Optimiser -
1/distinct =1/3=33.333%

Tue Nov 01, 06:44:00 AM EDT  

Anonymous Andreas said....

42 is the one and only answer.

Tue Nov 01, 07:00:00 AM EDT  

Blogger Paulo Vale said....

The question is incomplete and the percentages are there just for distraction.

The question could might be:
"I have four balls in a box, 1 red 1 green and 2 blue. What is the chance to get the right ball?"

The question should be something like: "What's the probability to get the blue ball on a random extraction"... or red or blue...

And if it expected to be blue, the answer would be 50%, red or green 25%.

Paulo Vale

Tue Nov 01, 07:10:00 AM EDT  

Blogger Grant Johnson said....

Make it hurt even more, exchange 60% for 0%

Tue Nov 01, 01:43:00 PM EDT  

Blogger Jeet said....

The question is about answering your chances to answer this question right.

Because this is random pick, hence if you are feeling very luck then choose C,
If you feeling 50 - 50 then choose B,
If you are not very sure then choose either A or B because both have same %.

It is all about your chances to pick the right answer to the question and can never be more than 60% :)

Else there is another option E) called One of these :)

Tue Nov 01, 07:57:00 PM EDT  

Blogger Dongwei Wang said....

selectivity=1/NDV=1/3=33%

Wed Nov 02, 02:50:00 AM EDT  

Anonymous Ackas said....

Its b)50%

There are two outcomes, you are either correct or you are not.

The chance of that is 50%.

Wed Nov 02, 06:49:00 AM EDT  

Anonymous James said....

The question is not asking to pick the choice,it is asking for the chance. The confusion is due to the chance which depends on the choice. Based on the choice, the chance is 33.3% , which is not part of the choice.

Wed Nov 02, 07:48:00 AM EDT  

Anonymous Anonymous said....

Looks like a paradox to me.

Given: four choices for answer
Assume: Correct answer is withing the four choices.

So...
Selecting correct answer at random is 1 in 4 or 25%. However, there are two answers of 25% so the chance or selecting 25% at random is 2 in 4, which is 50% and the chance of selecting 50% at random is 25%, so.....
We we have a paradox that selecting one answer affects the result in itself. Thus we cannot solve this paradox.

Thu Nov 03, 11:17:00 AM EDT  

Anonymous Andy C said....

If the actual probability is 33%, it means that it doesn't matter which one you choose - you will always be wrong.

The chance of getting it right from those choices is therefore 0%.

Thu Nov 03, 11:44:00 AM EDT  

Anonymous Anonymous said....

Let's rephrase:

If you chose an answer to this question at random, what is the chance you will be correct?
A. RED
B. BLUE
C. GREEN
D. RED


What now?

There is no question.

Hence, the problem translates to "what is the chance to correctly answer a non-existing question?"

If anything and if one must ... pretty slim ... 0%

G

Thu Nov 03, 03:02:00 PM EDT  

Blogger Jean-Marc Desvaux said....

The chance to pick 25% ( a or d) is 2/4, the chance to pick b or c is 1/4.
Meaning that whatever you pick, it won't match your chance to pick it.
So the probability is 0.
It's like the probabilty of getting a third side of a two faced coin.

Thu Nov 03, 04:27:00 PM EDT  

Anonymous Ackas said....

The question is this: -

If you choose an answer to this question at random, what is the chance you will be correct?

Forget for now that you have 4 choices.
Look at the question and try to answer it.

Either the answer is 50% (correct or not correct) or its almost 0% (there is a correct answer and an almost infintesimal chance of picking it at random).

Which one of those is an option when you look at the 4 possible answers?

Thu Nov 03, 05:46:00 PM EDT  

Blogger George Joseph said....

This comment has been removed by the author.

Fri Nov 04, 11:32:00 PM EDT  

Blogger George Joseph said....

If you choose to answer this question at random(and there is at least and atmost one answer to this question or exactly one answer to this question) what is the probability you are correct
a)100%
b)100%
c)100%
d)100%
--The answer is pretty clear here
100% chance you are correct
like wise if the choice are like
a)100
b)100
c)50
d)50
the answer should be 0.5(the right answer could be 100 or 50)
Since the question doesn't mention about the number of accurate answers to the question or whether the answer can be NOT in the 4 choices, it leads to a point of confusion.
Wish I had paid attention to the probability lessons at school!!

Fri Nov 04, 11:41:00 PM EDT  

Blogger George Joseph said....

If you choose to answer this question at random(and there is at least and atmost one answer to this question or exactly one answer to this question) what is the probability you are correct
a)100%
b)100%
c)100%
d)100%
--The answer is pretty clear here
100% chance you are correct
like wise if the choice are like
a)100
b)100
c)50
d)50
the answer should be 0.5(the right answer could be 100 or 50)
Since the question doesn't mention about the number of accurate answers to the question or whether the answer can be NOT in the 4 choices, it leads to a point of confusion.
Wish I had paid attention to the probability lessons at school!!

Fri Nov 04, 11:41:00 PM EDT  

Anonymous Anonymous said....

Tom, waiting for your answer...

Wed Nov 09, 10:52:00 AM EST  

Anonymous Ariq said....

Very interesting. I like it.

Wed Nov 23, 03:44:00 AM EST  

Anonymous Anonymous said....

the answer is...42

Tue Dec 13, 08:51:00 AM EST  

Blogger Common Sense said....

Hahaha you are all wrong. If you were to choose a random answer in the beginning, there would be no need for this mathematical nonsense. The answer is in the question. Your answer was random and so the posibility that you are correct is random. You base your probability on how you originally picked your answer. If you were ceratain you picked a correct answer on a test, than you must be correct. If you were certain you picked the wrong answer, you are wrong. If you are uncertain wether you picked a correct or incorrect answer you are not right nor are you wrong until you see how you scored. This question is basically playing with the knowledge of our own minds. We cannot be asked to choose an answer at random because is it of our minds nature to overanalyze. In the beginning, when we are asked to choose at random, our mind stresses the fact that we were told not to find a common difference or something that makes our "answer" stand out. Being asked a question we always work our way towards the answer through many processes. It would seem against our minds nature to have to make that kind of decision, which wasnt meant to even be a decision in the first place. Our minds simply cannot conquer the impossible. Having to choose or analyze means there was never such a thing as the random. The random can only be expressed as somethong that is exact only with relation to its limits, if any limits are present, and that does not follow any sort of pattern but simply exists as any variable within two points. When asked to find the posibility that we are correct, this theory applies equally as significant. For example; I am spinning a coin to see wether I get heads or tails. My chance of getting heads is equal to that of getting tails. I have a 50-50 chance. That does not mean that half of all my coin tosses will result with half the coins landing heads up or tails up, it means that for every toss, I have an equal chance of getting either heads or tails. I can toss the coin 100 times and it is possible that all the tosses will results with heads. Nevertheless, on my 101th toss, I still have a 50% chance of getting tails. The posibilities are always there, although the results are not accuratley 50-50 since both sidesof the coin have an equal chance of landing face up or face down. Lets say that before I made my first toss, I had to randomly pick a side that would win. Lets say I chose tails. With the kind of mathematics and theories you guys are using, I would have a 50% chance of being correct. So after the toss, I get heads. I try again. On that second toss, I have that same chance of getting heads again and again. So my chance would be, well, random. There is no winning side and there is no losing side, its simply random. Its any mans game. In this problem, we are asked to choose randomly. That means we are aware that the correct answer is also something random, or else, we would not have picked randomly in the first place. Though with this problem, one of the answers MUST be correct. To find The probability of our randomly chosen answer to be correct is fairly simple. Re-read the question. We need to find the probability of our randomly chosen answer to be correct. By doing this, the question would be false, because if we found the probability in the first place, we would have taken it into consideration and we would have chosen another answer calling it random although it wast, it was only based on our knowledge of the answers with relation within themselves as all the possible answers and wether or not one answer was superior towards being correct than the others. Heres the bottom line: There would be a probability that our answer was correct, although this probability would be random since the answer we chose was random itself. Thus, leaving us with the fact that all the possible answers (A,B,C, & D) have the possibility of being correct, proving that one cannot calculate the answer.

Wed Mar 28, 02:30:00 AM EDT  

Blogger Common Sense said....

If your choice was random, then your possibility of being correct is random.

Wed Mar 28, 02:33:00 AM EDT  

Blogger Thomas Kyte said....

@'Common Sense'

1) paragraphs. paragraphs are really nice

2) if your choice was random.... then your ....

If your mom was human, then your possibility of being blue is human.

doesn't make sense. Your possibility of being correct is a possibility - not "random".

Wed Mar 28, 07:18:00 AM EDT  

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