Logical Question

[shitboi]

Just a quick and fun question for programmers and those in process of learning programming basics.

This questions will require you to use reasoning skills to derive at the final answer.

Jane has told every one 10 dates, of which 1 is her correct birthday.
She then secretly told Ben her month of birth, and secretly told John her day of birth.

The following is the list of dates provided by Jane.

• March 4
• March 5
• March 8
• June 4
• June 7
• September 1
• September 5
• December 1
• December 2
• December 8

After listening to the Jane's whispers,
Ben said: If i don't know the answer, then John won't know it either.
John said: I didn't know it at first, but now I know it.
Ben said: Now i know it too.

Which day is Jane's birthday ?

So, if you have seen this question before, then keep it to yourself for now.
When posting replies, put in your reasoning.

I'll check back in 2 days

[KraHen]

#removed

Addendum : Jane is an *******, come on, who has fun with going to people telling them random dates.

[{ Angelius }]

The way i see it.. The day has to be 2 or 7 other wise John will never be able to deduce the correct answer without knowing the month too..

Sorting it by Day...
#1 occurs 2 times
#2 occurs 1 times
#4 occurs 2 times
#5 occurs 2 times
#7 occurs 1 times
#8 occurs 2 times

So for example if stupid Jane whispered the number 8 in John's ear John will still be as ignorant as he was before she whispered that number in his ear as the month could be March or December, And the fact that Ben couldn't deduce the answer by knowing the month only contributes the fact that the month occurs more than 1 time which is already known to both of them :|

My answer is based on your question... And i quote..

Originally Posted by shitboi

Which day is Jane's birthday ? [/B]

And based on that question I have a puzzle for you to solve..

How the **** did Ben deduce the Day just by knowing the fact that John deduced the answer by knowing that Ben couldn't deduce the answer just by knowing the month.

Your **** is missed up bro or is it meant to be misleading like that?

PS: You are a shitboi and I hate you

[KraHen]

Originally Posted by { Angelius }

The way i see it.. The day has to be 2 or 7 other wise John will never be able to deduce the correct answer without knowing the month too..

Sorting it by Day...
#1 occurs 2 times
#2 occurs 1 times
#4 occurs 2 times
#5 occurs 2 times
#7 occurs 1 times
#8 occurs 2 times

So for example if stupid Jane whispered the number 8 in John's ear John will still be as ignorant as he was before she whispered that number in his ear as the month could be March or December, And the fact that Ben couldn't deduce the answer by knowing the month only contributes the fact that the month occurs more than 1 time which is already known to both of them :|

My answer is based on your question... And i quote..


And based on that question I have a puzzle for you to solve..

How the **** did Ben deduce the Day just by knowing the fact that John deduced the answer by knowing that Ben couldn't deduce the answer just by knowing the month.

Your **** is missed up bro or is it meant to be misleading like that?

PS: You are a shitboi and I hate you

Hint : you`re really close, try thinking in reverse.

[shitboi]

This question is actually a real interview question that has brutally slaughtered many people.

Here is the solution.

Let's ask ourselves why Ben said that "if he doesn't know the answer, John won't know"
- the only way to know the correct answer is IF they are told either a month or day that is unique in the given list.
- obviously no unique month in the list, but could John be informed of a day that is unique in the list?
- Ben knows the correct month, so he must have checked the dates (June 7, and Dec 2) that has a unique day value.
- After checking none of these unique day has an associated month value that matches the correct month he knows.
- hence he made the comment above

When John heard Ben's comment, he began to think

- Since June 7, and Dec 2 is definitely not the correct day, plus Ben knows the month, he can directly rule out June and Dec options
- He is now left with
 March 4
 March 5
 March 8
 September 1
 September 5
- Then John said he knew the answer, since he know the correct day of birth, this day must be a unique number in the remaining list
- therefore we are left with only
 March 4
 March 8
 September 1

Then Ben said he knows the correct date too.
- Since Ben knows the correct month of birth, the only unique month left in the list is September.

Hence the correct answer is September 1.

Conclusion, Ben and John are ******* smart. So are you now

[Best Coder 2014]

Originally Posted by shitboi

This question is actually a real interview question that has brutally slaughtered many people.

Lol, for what kind of retarded job was this an actual interview question?

[shitboi]

I think it was a management position.

#Edit, but was later used for other positions as well. I got this question from a coding group

[OverKillasdwqe]

Originally Posted by shitboi

This question is actually a real interview question that has brutally slaughtered many people.

Here is the solution.

Let's ask ourselves why Ben said that "if he doesn't know the answer, John won't know"
- the only way to know the correct answer is IF they are told either a month or day that is unique in the given list.
- obviously no unique month in the list, but could John be informed of a day that is unique in the list?
- Ben knows the correct month, so he must have checked the dates (June 7, and Dec 2) that has a unique day value.
- After checking none of these unique day has an associated month value that matches the correct month he knows.
- hence he made the comment above

When John heard Ben's comment, he began to think

- Since June 7, and Dec 2 is definitely not the correct day, plus Ben knows the month, he can directly rule out June and Dec options
- He is now left with
 March 4
 March 5
 March 8
 September 1
 September 5
- Then John said he knew the answer, since he know the correct day of birth, this day must be a unique number in the remaining list
- therefore we are left with only
 March 4
 March 8
 September 1

Then Ben said he knows the correct date too.
- Since Ben knows the correct month of birth, the only unique month left in the list is September.

Hence the correct answer is September 1.

Conclusion, Ben and John are fucking smart. So are you now

why did you rule out dec
for what bens know at the very first that it's some month
then john knew it's a month that has more than 1 date left and as it's neither 2 or 7 you can rule them out also you can rule out june as it only has 1 date left !
so you are left with
March 4
March 5
March 8
September 1
September 5
December 1
December 8

which is going to left you with march 4 , which was my answer that i was stupid enough to delete before thinking :\

[shitboi]

Originally Posted by OverKillasdwqe

why did you rule out dec
for what bens know at the very first that it's some month
then john knew it's a month that has more than 1 date left and as it's neither 2 or 7 you can rule them out also you can rule out june as it only has 1 date left !
so you are left with
March 4
March 5
March 8
September 1
September 5
December 1
December 8

which is going to left you with march 4 , which was my answer that i was stupid enough to delete before thinking :\

Your deduction as an observer has left out Ben's comment of : "if i don't know, then john won't know", and doesn't account for why he said that either.

Ben, started out with multiple choices to choose from, he doesn't know which is the absolute correct answer. So he put himself in John's shoes. If John were to quickly find the right answer, he will have to look at unique day values first. Only 2 options has unique day value. but their month value is definitely wrong, leaving John to select from repeating values.

Therefore he has the right to claim if he doesn't know, then john won't know.

Based on your answer, you are in agreement that June 7, and December 2 should be ruled out, and it is Ben who knows the month, ruled those 2 options out, hence June and December is definitely not the correct month.

This is the reason to rule out june and dec completely. This will hence change your list of date remaining.

[Ultimation]

im too drunk to read this ****, are you bored?

[OverKillasdwqe]

Originally Posted by shitboi

Your deduction as an observer has left out Ben's comment of : "if i don't know, then john won't know", and doesn't account for why he said that either.

Ben, started out with multiple choices to choose from, he doesn't know which is the absolute correct answer. So he put himself in John's shoes. If John were to quickly find the right answer, he will have to look at unique day values first. Only 2 options has unique day value. but their month value is definitely wrong, leaving John to select from repeating values.

Therefore he has the right to claim if he doesn't know, then john won't know.

Based on your answer, you are in agreement that June 7, and December 2 should be ruled out, and it is Ben who knows the month, ruled those 2 options out, hence June and December is definitely not the correct month.

This is the reason to rule out june and dec completely. This will hence change your list of date remaining.

again you still should not have ruled out the rest of dec !
lets state the fact

john's day must not be unique number (rule out 2 and 7) at the very first
ben's month must have multiple dates (rule out the rest of june)

you said " but their month value is definitely wrong " , well for june it only had 2 dates, if one is rules out it means you have to rule out the other as ben had a month with multiple dates, but why dec. !

when he said "if i don't know" it means that he have a month with multiple dates in it that he couldn't decide which is the right day

"then john won't know" it means giving the right day isn't enough as it occures in more than one month !! (which is what he assumed)

but john said "I didn't know it at first" which means he didn't know the right answer (mean it wasn't a unique one as ben assumed, that rules out 7 and 2) and now he is left with

March 4
March 5
March 8
June 4
September 1
September 5
December 1
December 8

then he rules out the months with 1 date

March 4
March 5
March 8
September 1
September 5
December 1
December 8

" but now I know it" which means that for him to know, it MUST be a unique number which is 4

which also apply the rules we had (happens in a month with multiple dates, not a unique number at the very first)

[Queenieyu]

i am so confusing till now. lol.....