Interesting maths question, what's the answer?

[llamatron]

if there were 4 different numbers it would be 25% but there are 3 answers with 1 being doubly likely to be selected.

 

A

A

B

C

 

so the probability of A being correct is 1/3, the probability of picking it is 1/2. The probability of B or C being the answer is 1/3 and 1/3, the probability of selecting them is 1/4 and 1/4. So I think you are looking at a serial probability question (but I can't remember how to do them).

 

Is it 1/3*1/2+1/3*1/4+1/3*1/4

 

0.33333333

 

of course I am assuming the numbers in the question were random and could have been AABC.

 

EDIT: oh but if the answer is supposed to be one of the multiple choice answers then clearly the question is a joke and the answer is 0% or 100%. I find attempting maths more fun.

 

Mathematically 0.333333

Philosophically 0 or 100%

 

It depends how you decide to view the question

[gnvqsos]

If you choose an answer at random what is the probability of being correct?

 

A) 25%

B) 50%

C) 60%

D) 25%

 

This is invalid as responses must be arranged in a sequence ie 25,25, 50 or 60 or the reverse.you have failed the examiners test and are disqualified.

[Cyclone]

There are many possible random answers which I will express as infinity (∞) and only one correct answer.

Answer 1-∞

 

There were only 4 possible answers, they were listed as A to D.

 

1 - infinity is simply -infinity. How can that be the 'correct' answer?

 

---------- Post added 29-11-2012 at 21:41 ----------

 

if there were 4 different numbers it would be 25% but there are 3 answers with 1 being doubly likely to be selected.

 

A

A

B

C

 

so the probability of A being correct is 1/3, the probability of picking it is 1/2. The probability of B or C being the answer is 1/3 and 1/3, the probability of selecting them is 1/4 and 1/4. So I think you are looking at a serial probability question (but I can't remember how to do them).

 

Is it 1/3*1/2+1/3*1/4+1/3*1/4

 

0.33333333

 

of course I am assuming the numbers in the question were random and could have been AABC.

 

EDIT: oh but if the answer is supposed to be one of the multiple choice answers then clearly the question is a joke and the answer is 0% or 100%. I find attempting maths more fun.

 

Mathematically 0.333333

Philosophically 0 or 100%

 

It depends how you decide to view the question

 

I don't think your attempt at serial probability works. The question is deliberately posed so that as you select the chance of guessing as 1/4 that then changes to 1/2 which then makes the 1/2 logically incorrect as the chance of guessing the answer which says 1/2 is only 1/4. There is no correct answer to the question.

[Alcoblog]

If you choose an answer at random what is the probability of being correct?

 

A) 25%

B) 50%

C) 60%

D) 25%

 

Surely, if you chose an answer at random, the answer is going to be either right or wrong. Therefore, I'd say 50%.

[maxmaximus]

There were only 4 possible answers, they were listed as A to D.

 

1 - infinity is simply -infinity. How can that be the 'correct' answer?

 

 

Says who? The OP simply asked us to choose a random answer; they didn't say it had to be one from the list.

 

Infinite can be used to describe an unknown but very large number.

[llamatron]

There were only 4 possible answers, they were listed as A to D.

 

1 - infinity is simply -infinity. How can that be the 'correct' answer?

 

---------- Post added 29-11-2012 at 21:41 ----------

 

 

I don't think your attempt at serial probability works. The question is deliberately posed so that as you select the chance of guessing as 1/4 that then changes to 1/2 which then makes the 1/2 logically incorrect as the chance of guessing the answer which says 1/2 is only 1/4. There is no correct answer to the question.

 

I don't understand what you are saying. If we are talking mathematically its the probably from before you select anything that should be calculated. I think the maths is right but I am not sure that is the question.

 

There is also the option that as long as you put no thought into why you select something the answer is 100% because you just have to pick randomly.

 

The answer is-the question is badly worded!

[Cyclone]

In order to calculate the probably of a random pick from the four possible answers being correct you have to know how many of the answers are correct.

 

It's a paradox.

 

(Yes, the question is badly worded, the original from which it is copied is more carefully worded).

[maxmaximus]

In order to calculate the probably of a random pick from the four possible answers being correct you have to know how many of the answers are correct.

 

It's a paradox.

 

(Yes, the question is badly worded, the original from which it is copied is more carefully worded).

 

You are still reading something that is not in the OP's post, it does not say the random answer has to be from the list.

[Cyclone]

You are still reading something that is not in the OP's post, it does not say the random answer has to be from the list.

 

The implication is there, it was just badly worded.

 

The original question from which it was listed (linked on page 1 I believe) is more specific.

 

Without that implication it makes even less sense than currently.

[maxmaximus]

The implication is there, it was just badly worded.

 

The original question from which it was listed (linked on page 1 I believe) is more specific.

 

Without that implication it makes even less sense than currently.

 

I take it you mean this question.

 

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

 

random

Made, done, happening, or chosen without method or conscious decision:

 

I came up with the random answer of Jar.

 

If I had chosen an answer from the list it wouldn't have been a random answer, because I would have used method and conscious thought to select it.

 

My answer of jar is extremely likely to be the incorrect answer and because there are infinite possible random answers the possibility of getting it right is 1 - ∞