# Anyone want to try to solve this riddle? **URL:** \ **Category:** Factual Questions\ **Created:** [October 31, 2011, 12:08am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335 "2011-10-31T00:08:00Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![copperwindow](https://avatars.discourse-cdn.com/v4/letter/c/4af34b/32.png) [@copperwindow](https://boards.straightdope.com/u/copperwindow)\ **Post date:** [October 31, 2011, 12:08am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/1 "2011-10-31T00:08:00Z")
If you choose an answer to this question at random, what is the chance you will be correct? A) 25% B) 50% C) 0% D) 25% ---
**Author:** ![Meatros](https://avatars.discourse-cdn.com/v4/letter/m/b4bc9f/32.png) [@Meatros](https://boards.straightdope.com/u/Meatros)\ **Post date:** [October 31, 2011, 12:12am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/2 "2011-10-31T00:12:22Z")
> [@copperwindow](#): > > If you choose an answer to this question at random, what is the chance you will be correct? > > A) 25% > B) 50% > C) 0% > D) 25% Which question? The one in the thread title (anyone want to try to solve this riddle?) or the one in the OP? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [October 31, 2011, 12:12am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/3 "2011-10-31T00:12:32Z")
That’s interesting… I guess I’d say “none of the above.” ---
**Author:** ![copperwindow](https://avatars.discourse-cdn.com/v4/letter/c/4af34b/32.png) [@copperwindow](https://boards.straightdope.com/u/copperwindow)\ **Post date:** [October 31, 2011, 12:17am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/4 "2011-10-31T00:17:02Z")
> [@Meatros](#): > > Which question? The one in the thread title (anyone want to try to solve this riddle?) or the one in the OP? The one in the op. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 31, 2011, 12:20am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/5 "2011-10-31T00:20:02Z")
B. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [October 31, 2011, 12:25am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/6 "2011-10-31T00:25:11Z")
Probably none of the above. It has the smell of the liar’s paradox. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [October 31, 2011, 12:27am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/7 "2011-10-31T00:27:06Z")
C is supposed to be 60%. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [October 31, 2011, 12:28am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/8 "2011-10-31T00:28:32Z")
Wait… That wasn’t right. Ignore this post. ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [October 31, 2011, 12:33am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/9 "2011-10-31T00:33:17Z")
> [@copperwindow](#): > > If you choose an answer to this question at random, what is the chance you will be correct? > > A) 25% > B) 50% > C) 0% > D) 25% There is no correct answer. A and D cannot be correct because there is a 50% chance that I will pick them but then the correct answer is B. B cannot be correct because there is a 25% chance I pick it, but then the correct answer is A or D. C cannot be correct because there is a 25% chance I pick it but then the answer cannot be correct, since I picked it. ---
**Author:** ![Lord\_Mondegreen](https://avatars.discourse-cdn.com/v4/letter/l/91b2a8/32.png) [@Lord\_Mondegreen](https://boards.straightdope.com/u/Lord_Mondegreen)\ **Post date:** [October 31, 2011, 12:34am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/10 "2011-10-31T00:34:59Z")
OK, I’ll give it a go. Assume each answer in turn is correct (ignoring that the answers are percentages) and then see what the implications of that are (by _not_ ignoring that the answers are percentages). If A) is correct, then you have a 50% chance of getting it right, since it also means that D) is correct. But if the answer is 50%, then A) isn’t correct, and so neither is D). If B) is correct, then you have a 25% chance of getting it right. However B) is actually “50%,” so B) can’t be correct. Similarly if C) is correct, then you have a 25% chance of getting it right. However C) is actually “0%,” so C) can’t be correct. So, as others have said, “None of the above.” Or, on edit, what **RickJay** said. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [October 31, 2011, 12:35am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/11 "2011-10-31T00:35:17Z")
> [@John\_Mace](#): > > C is supposed to be 60%. Yes. For reference, here’s a correct version: **If you choose an answer to this question at random, what is the chance you will be correct?** A. 25% B. 50% C. 60% D. 25% [Citation](http://www.quora.com/If-you-choose-an-answer-to-this-question-at-random-what-is-the-chance-you-will-be-correct-A-25-B-50-C-60-D-25), [citation](http://www.reddit.com/r/math/comments/c2p7u/multiple_choice_if_you_choose_an_answer_to_this/). ---
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [October 31, 2011, 1:04am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/12 "2011-10-31T01:04:11Z")
Ah, beaten to the punch. The OP has the wrong question. ---
**Author:** ![Dr.Love](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@Dr.Love](https://boards.straightdope.com/u/Dr.Love)\ **Post date:** [October 31, 2011, 1:54am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/13 "2011-10-31T01:54:42Z")
This riddle would be easily resolved if we allow for non-uniform random choices. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 31, 2011, 2:02am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/14 "2011-10-31T02:02:05Z")
> [@John\_Mace](#): > > C is supposed to be 60%. Doesn’t matter. If you’re picking uniformly at random, there’s no value you can put in C to make the question answerable. ---
**Author:** ![Carmady](https://avatars.discourse-cdn.com/v4/letter/c/f04885/32.png) [@Carmady](https://boards.straightdope.com/u/Carmady)\ **Post date:** [October 31, 2011, 2:12am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/15 "2011-10-31T02:12:08Z")
0%. The question does not explicitly state that you have to choose A, B, C, or D. I take it that I am choosing an answer from an uncountably infinite set. 0% is the correct answer, and I might choose it, but nevertheless my chance of choosing it is 0%. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [October 31, 2011, 3:14am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/16 "2011-10-31T03:14:33Z")
> [@ultrafilter](#): > > Doesn’t matter. If you’re picking uniformly at random, there’s no value you can put in C to make the question answerable. 50% would do it, wouldn’t it? ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 31, 2011, 3:14am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/17 "2011-10-31T03:14:54Z")
> [@Carmady](#): > > 0%. > > The question does not explicitly state that you have to choose A, B, C, or D. > > I take it that I am choosing an answer from an uncountably infinite set. 0% is the correct answer, and I might choose it, but nevertheless my chance of choosing it is 0%. I don’t see this as a reasonable interpretation of what was written. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 31, 2011, 4:23am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/18 "2011-10-31T04:23:02Z")
> [@Rysto](#): > > 50% would do it, wouldn’t it? Yeah, it would. Nice catch. ---
**Author:** ![Farmer\_Jane](https://avatars.discourse-cdn.com/v4/letter/f/bbe5ce/32.png) [@Farmer\_Jane](https://boards.straightdope.com/u/Farmer_Jane)\ **Post date:** [October 31, 2011, 4:31am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/19 "2011-10-31T04:31:42Z")
1. The options are ‘correct’ and ‘incorrect’. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [October 31, 2011, 7:20am UTC](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335/20 "2011-10-31T07:20:43Z")
> [@CitizenPained](#): > > 1. > > The options are ‘correct’ and ‘incorrect’. Remind me to play poker with you some time. [Next page](https://boards.straightdope.com/t/anyone-want-to-try-to-solve-this-riddle/601335.md?page=2)