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The professor for class Logic 315 says on Friday: "We're going to have a surprise quiz next week, but I'm not telling you what day... if you can figure out what day it will be on, I'll cancel the quiz."
The students get together and decide that the quiz can't be on Friday, as if the quiz doesn't happen by Thursday, it'll be obvious the quiz is on Friday. Similarly, the quiz can't be on Thursday, because we know it won't be on Friday, and if the quiz doesn't happen by Wednesday, it'll be obvious it's on Thursday (because it can't be on Friday). Same thing for Wednesday, Tuesday and Monday. So it can't be on ANY day, so there's no quiz next week!"
They tell the professor, who smiles and says, "Well, nice to see you're thinking about it."
On Tuesday, the professor gives the quiz, totally unexpected!
The only information that the students are given is, "There is going to be a surprise quiz next week." They don't know anything else. Therefore, I think the students got it wrong from the beginning by thinking that it can't be on Friday. I don't see any logical reason on why it can't be on Friday (or any other day). The quiz will be a surprise to them as long as there is no way of knowing exactly what day it will be given, and given the information they know about the quiz, I think it's impossible to know that. So, the quiz can be given on any day the Professor wants and it will still be a surprise quiz (even though it's not much of a surprise if they're already told that it's going to be on some day during the week).
However, if the students come to the conclusion that there is going to be no surprise quiz at all, then, of course, the Professor can just surprise them by giving the quiz on any day.
Assuming that It can't be Friday, because that would make the surprise not a surprise. It's logical to assume it won't be Friday, or over the weekend. It won't be on Monday because that wouldn't give them time to guess. It can't be Thursaday because we know it's not Friday and if it hasn't happened by Wed. then it's obviously Thursday. That's for sure not on Mon., Thursday or Friday. I can't see logic getting me any closer to 50/50. IDK
"There ought to be a term that would designate those who actually follow the teachings of Jesus, since the word 'Christian' has been largely divorced from those teachings, and so polluted by fundamentalists that it has come to connote their polar opposite: intolerance, vindictive hatred, and bigotry." -- Philip Stater, Huffington Post
always working on cleaning my windows- me regarding Johari
This is some kind of paradox Adrian. Logically it's deducable, but not proven that it can't be Friday, because they would know by Thursday. If we go with this assumption we end up with numerically it can't be any day next week, as you see above. That mean logically either the premise is false or the teacher is lying. He didn't say you couldn't give more than one answer. It's reasonable to assume that there is in fact a quiz next week and that it won't be on Friday, based on that trust. I'd tell the teacher it is on Monday, then on Monday I'd say it was on Tuesday, etc. and on Friday I's say you can't have it today,because we expect it, therefore you were lying and there is no quiz this week. Other than that a surprise quiz could be any day, because he's not following the premise it's a surprise pop quiz or following standard logic. He could theoretically come in and surprise them on any day unless they made a prediction every day.
Also the premise It can't be Friday is only good ON Thursday, so up until Thursday that could be the logical plan. There's some kind of paradox or time thing I'm still not getting exactly
"There ought to be a term that would designate those who actually follow the teachings of Jesus, since the word 'Christian' has been largely divorced from those teachings, and so polluted by fundamentalists that it has come to connote their polar opposite: intolerance, vindictive hatred, and bigotry." -- Philip Stater, Huffington Post
always working on cleaning my windows- me regarding Johari
(April 5, 2011 at 12:44 am)Tiberius Wrote: The professor for class Logic 315 says on Friday: "We're going to have a surprise quiz next week, but I'm not telling you what day... if you can figure out what day it will be on, I'll cancel the quiz."
The students get together and decide that the quiz can't be on Friday, as if the quiz doesn't happen by Thursday, it'll be obvious the quiz is on Friday. Similarly, the quiz can't be on Thursday, because we know it won't be on Friday, and if the quiz doesn't happen by Wednesday, it'll be obvious it's on Thursday (because it can't be on Friday). Same thing for Wednesday, Tuesday and Monday. So it can't be on ANY day, so there's no quiz next week!"
They tell the professor, who smiles and says, "Well, nice to see you're thinking about it."
On Tuesday, the professor gives the quiz, totally unexpected!
What's the flaw in the students' thinking?
Wishful Thinking?
Comparing the Universal Oneness of All Life to Yo Mama since 2010.
I was born with the gift of laughter and a sense the world is mad.
April 7, 2011 at 9:36 pm (This post was last modified: April 7, 2011 at 9:37 pm by Rayaan.)
OR, maybe the Professor thought that the students will think that the least surprising day for the surprise quiz would be Tuesday since Tuesday is Chooseday.
Aha.. my mistake was trying to figure out why it was on Tuesday
There was no flaw in their logical deduction, it was a flaw in their premise. The premise "It can't be on Friday because we would know Thursday" Is only good on Thursday and can't be factored in prior to that point in time. It would also make the teacher into a liar and we would have no reliability in anything he stated. Base assumption is unstated that the teacher is telling the truth. In reality he could have given it on any day, if what the teacher says can be trusted, well... any day but Friday. . That's my story and I'm sticking to it.
"There ought to be a term that would designate those who actually follow the teachings of Jesus, since the word 'Christian' has been largely divorced from those teachings, and so polluted by fundamentalists that it has come to connote their polar opposite: intolerance, vindictive hatred, and bigotry." -- Philip Stater, Huffington Post
always working on cleaning my windows- me regarding Johari
![[Image: harmlesskitchen.png]](https://i.postimg.cc/yxR97P23/harmlesskitchen.png)
. That's my story and I'm sticking to it.
