Avicus Archive

Logic Problem for Teens (Apparently...) by _Gill August 9, 2015 at 2:08 AM UTC

Hey everyone!
Max here with another strange problem. This one isn't necessarily math, but I would say its almost impossible to solve (even if its only a logic problem). I found this problem while reading BBC News: Its a problem Singapore used to measure teenagers ability to think logically (at least I'm pretty sure what it was... I know it was for teens), and it baffled the world. If you think you can solve this mind numbing puzzle, good luck!!!

"Albert and Bernard just become friends with Cheryl, and they want to know when Cheryl's birthday is. Cheryl gives them a list of possible dates. 
 
May 15                May 16            May 19
June 17               June 18
July 14                July 16
August 14           August 15       August 17

Cheryl then tells Albert and Bernard separately the month and day of her birthday respectively.

Albert: I do not know when Cheryl's birthday is, but I know Bernard does not know too.
Bernard: At first I don't know when Cheryl's birthday is, but I know now.
Albert: Then I also know when Cheryl's birthday is.

So when is Cheryl's birthday?"


Good luck on your endeavors! I hope someone gets it (Please do not look up or link content. Just guess and show logical reasoning).

-Max

_Phyre August 9, 2015 at 2:08 AM UTC

June 18th

rinn August 9, 2015 at 2:08 AM UTC

July 16th

Gundham August 9, 2015 at 2:08 AM UTC

Adobe Flash Player.exe has stopped working.

SnowSX3 August 9, 2015 at 2:08 AM UTC

Damnit, I used to know how to solve this problem.
It's a case of trial and error with the given dates.

It is possible to find the answer with the information given, I just can't remember how to do it xD

resepignev August 9, 2015 at 2:08 AM UTC

It's may 15, if you add both numbers together and subtract the amount of letters from the sum you get 3 => 3 sides => triangle => illuminati. But July 16 also equals 3. To determinate what date it is, you have to add the amount of the letters to the sum of the numbers. Now for may 15 you'll get 9 and for July 16 you get 11. Now if you subtract the 3 from the first calculation from 9 (second calculation) you get 6. Now you did 3 calculations. 3 times the 6 is 666 also known as the number of the devil. Since Cheryl is the name of the devils wife in some religions or such it's confirmed that may 15 is the birthday of the devils wife and the date of the founding of the illuminati.

Emmaye August 9, 2015 at 2:08 AM UTC

July 14th?

DaFrozenBlaze August 9, 2015 at 3:08 AM UTC

YESSS CHERYL's BIRITHDAY WOOOO

July 16th, I'm SIngaporean :D

goldenwalrus909 August 9, 2015 at 3:08 AM UTC

Ok, since Albert told Bernard he (Bernard) doesn't know, it means it must be a month in which the date is similar to another (Bernard has options to guess from). Thus, the only pairs are [May 15, August 15],[May 16, July 16],[June 17, August 17], and [July 14, August 14]. Since June 18 is no longer an option, the updated list goes as follows: 
May 15                May 16            May 19
June 17          
July 14                July 16
August 14            August 17

As you can see, June now only has one option: the 17th, driving Bernard to state how he now knows.

That's what I've gotten out of it, at least :P

JUBBINATOR August 9, 2015 at 3:08 AM UTC

July 16
Dis b mah logic ya'll
If Albert know dat Bernard aint know, dat means it can't be in a month where der is a number dat aint repeated, so since 19 and 18 aint repeated it cant be May and June
But now since May and June is gone we can discard dem, and with the remaining dates we know dat 14 repeats itself so Albert aint know if they was the answer, so it can't be a 14.
So Now cos Albert knows den if Bernard knows he cant have been told August, cos if Bernard knew he cant tell btwn which august it is; but if he was told July den he'd know which one it is cos der is only 1 option.
I think i did it :D

goldenwalrus909 August 9, 2015 at 3:08 AM UTC

YESSS CHERYL's BIRITHDAY WOOOO

July 16th, I'm SIngaporean :D
Dang, I tried my best x3

DaFrozenBlaze August 9, 2015 at 4:08 AM UTC

July 16
Dis b mah logic ya'll
If Albert know dat Bernard aint know, dat means it can't be in a month where der is a number dat aint repeated, so since 19 and 18 aint repeated it cant be May and June
But now since May and June is gone we can discard dem, and with the remaining dates we know dat 14 repeats itself so Albert aint know if they was the answer, so it can't be a 14.
So Now cos Albert knows den if Bernard knows he cant have been told August, cos if Bernard knew he cant tell btwn which august it is; but if he was told July den he'd know which one it is cos der is only 1 option.
I think i did it :D
Yes you did <3

ProfessorUtonium August 9, 2015 at 4:08 AM UTC

July 16th

PokerFace August 9, 2015 at 5:08 AM UTC

Da heck

JUBBINATOR August 9, 2015 at 6:08 AM UTC

Yes you did <3
<3
Am so proud ^_^

ImRaging August 9, 2015 at 3:08 PM UTC

This problem is so old, i remember watching a video of how to solve it in class

Javipepe August 9, 2015 at 8:08 PM UTC

I remember there was a thread somewhere on the Internet where I posted my reasoning, and they told me it was incorrect, but it was just a simple subtraction mistake hehe. 

But I think I recall it was may or July 16, can't remember

voidloop August 9, 2015 at 8:08 PM UTC

July 16th?

_Gill August 9, 2015 at 9:08 PM UTC

The correct answer is July 16th. Jubb's answer and explanation are perfect. Hahahaha. Good job everyone who got it legitimately!