User not logged in - login - register
Home Calendar Books School Tool Photo Gallery Message Boards Users Statistics Advertise Site Info
go to bottom | |
 Message Boards » » Surprise Test Page [1]  
God
All American
28747 Posts
user info
edit post

The teacher announced that there will be a surprise test next week.

The class meets on Monday, Wednesday, and Friday. If the test is given on Friday, then on Thursday I would be able to predict that the test is on Friday. It would not be a surprise.

Can the test be given on Wednesday? No, because on Tuesday I would know that the test will not be on Friday (thanks to the previous reasoning) and know that the test was not on Monday (thanks to memory). Therefore, on Tuesday I could foresee that the test will be on Wednesday. A test on Wednesday would not be a surprise.

Could the surprise test be on Monday? On Sunday, the previous two eliminations would be available to me. Consequently, I would know that the test must be on Monday. So a Monday test would also fail to be a surprise. Therefore, it is impossible for there to be a surprise test.

Can the teacher give a surprise test?

[Edited on February 24, 2010 at 1:32 PM. Reason : ]

2/24/2010 1:31:40 PM

FroshKiller
All American
51908 Posts
user info
edit post

wtf you wouldn't be able to make both of the first eliminations on sunday

the second hinges entirely on you having gone to class and not having had a test monday

2/24/2010 2:49:37 PM

Stein
All American
19842 Posts
user info
edit post

If you know there's going to be a test, it's not a surprise.

2/24/2010 2:54:04 PM

jethromoore
All American
2529 Posts
user info
edit post

How can a test be a surprise if you are forewarned about it? The day it occurs on could be a surprise as you will be surprised Monday and Wednesday if the teacher decides to wait until Friday.

In other words, if you expect something to happen every single day, then how is going to surprise you? What you expect doesn't happen, that's how.

2/24/2010 2:54:55 PM

God
All American
28747 Posts
user info
edit post

But it's so simple. All I have to do is divine from what I know of you: are you the sort of man who would put the quiz on Friday or Monday? Now, a clever man would put the quiz on Friday, because he would know that only a great fool would expect a quiz on Friday. I am not a great fool, so I can clearly not study for the quiz on Friday. But you must have known I was not a great fool, you would have counted on it, so I can clearly not study for the quiz on Monday.

2/24/2010 2:55:18 PM

neolithic
All American
706 Posts
user info
edit post

I forgot what undergrad class I first heard this reductio ad absurdum paradox before, it was definitely as CSC class though. Obviously, if you could move backward through time this question would be a paradox, but if we're allowing backward time travel this paradox is the least of our concerns.

Also:
http://xkcd.com/246/

2/24/2010 4:49:00 PM

catalyst
All American
8704 Posts
user info
edit post

shut the fuck up

2/24/2010 4:51:29 PM

God
All American
28747 Posts
user info
edit post

You only think I guessed wrong! That's what's so funny! I switched test dates when your back was turned! Ha ha! You fool! You fell victim to one of the classic blunders - The most famous of which is "never get involved in a land war in Asia" - but only slightly less well-known is this: "Never go against a Sicilian when test grades are on the line"! Ha ha ha ha ha ha ha! Ha ha ha ha ha ha ha! Ha ha ha--

2/24/2010 7:16:31 PM

howaboutno
Veteran
471 Posts
user info
edit post

How has zero people gotten this yet?

2/24/2010 7:36:38 PM

BobbyDigital
Thots and Prayers
41777 Posts
user info
edit post

I don't think that's the case.

It's just not as clever as he thinks it is.

2/24/2010 9:34:43 PM

neolithic
All American
706 Posts
user info
edit post

I think we have all seen "The Princess Bride" before, but I have heard this posed elsewhere before.

Oh, now I remember... We talked about this in an e-commerce class when discussing the auction concept of "cheap talk". I think he even showed the clip from this part of the movie. I suppose that makes this an unintentional excellent parody.

2/24/2010 11:30:35 PM

jethromoore
All American
2529 Posts
user info
edit post

^I think most people know it as the more famous example: the hangman paradox. A judge sentences a man to be hanged next week, the day will be a surprise. The prisoner reasons that he will not be hanged next week because it will not be a surprise following the same logic in the OP.

2/25/2010 12:51:05 PM

CalledToArms
All American
22025 Posts
user info
edit post

^thats what I was thinking too.

It was worded a little funky the first time I read it in the OP, but I guess it gets the point across.

From wikipedia (for people who haven't heard of this "paradox" before):

Quote :
"A judge tells a condemned prisoner that he will be hanged at noon on one weekday in the following week but that the execution will be a surprise to the prisoner. He will not know the day of the hanging until the executioner knocks on his cell door at noon that day. Having reflected on his sentence, the prisoner draws the conclusion that he will escape from the hanging. His reasoning is in several parts. He begins by concluding that the "surprise hanging" can't be on a Friday, as if he hasn't been hanged by Thursday, there is only one day left - and so it won't be a surprise if he's hanged on a Friday. Since the judge's sentence stipulated that the hanging would be a surprise to him, he concludes it cannot occur on Friday. He then reasons that the surprise hanging cannot be on Thursday either, because Friday has already been eliminated and if he hasn't been hanged by Wednesday night, the hanging must occur on Thursday, making a Thursday hanging not a surprise either. By similar reasoning he concludes that the hanging can also not occur on Wednesday, Tuesday or Monday. Joyfully he retires to his cell confident that the hanging will not occur at all. The next week, the executioner knocks on the prisoner's door at noon on Wednesday — which, despite all the above, will still be an utter surprise to him. Everything the judge said has come true."


[Edited on February 25, 2010 at 1:02 PM. Reason : ]

2/25/2010 1:02:11 PM

bdmazur
?? ????? ??
14957 Posts
user info
edit post

I've just decided to switch our Friday schedule to Monday, which means that the test we take each Friday, on what we learned during the week, will now take place on Monday, before we've learned it. But, since today is Tuesday, it doesn't matter in the slightest.

3/3/2010 1:42:09 AM

FroshKiller
All American
51908 Posts
user info
edit post

(Today is Wednesday.)

3/3/2010 9:20:31 AM

bdmazur
?? ????? ??
14957 Posts
user info
edit post

^its another movie quote

3/3/2010 12:57:01 PM

FeebleMinded
Finally Preemie!
4472 Posts
user info
edit post

Quote :
"I don't think that's the case.

It's just not as clever as he thinks it is."

4/6/2010 12:09:23 PM

 Message Boards » Study Hall » Surprise Test Page [1]  
go to top | |
Admin Options : move topic | lock topic

© 2024 by The Wolf Web - All Rights Reserved.
The material located at this site is not endorsed, sponsored or provided by or on behalf of North Carolina State University.
Powered by CrazyWeb v2.39 - our disclaimer.