Surprise Examination Problem
This puzzle puzzles me the most. It is a very famous one and many of you might have already encountered it.
so I guess the logic goes: he can't give a surprise test on friday, because if there's no test by then, the students will know it's on friday. Also, by the same token, thursday is no good, etc.
That exactly is the paradox. There seems to be no flaw in the argument for his being not able to give the exam.
Speaking from experience, if a prof. promised a surprize test "next week" and gave it on monday of that week, I would be very surprised :)
Can the professor say on Monday that the test will occur on Wednesday and then actually give the test on Tuesday?
It's a backwards reasoning fallacy, assuming that the students know on *Thursday* that the test is going to be on Friday. Let's go through it:
This can be done.Say the professor didn't conduct the exam in the first four days.So now it's friday and students are sure that there won't be any exam today since the professor can't surprise them.Now if he conducts the exam ,the students will be surprised.
Fog Creek Home