True. Well, Bernard already knows the day. If he knew the month, he'd know the entire date. So saying he doesn't know the entire date is the same as saying he doesn't know the month.
I donno but im 90 % sure im right and im pretty good with these these things. Put it this way... albert couldnt make his first statement if Cheryl told Benard 19. Ill consede if you find a better logic.
But albert doesnt know if Cheryl to Benard the 19th or not ... which would invalidated all the corresponding days in may or at least make albert not so sure Benard knows the exact day
You already have it. Look: Why? The only way Bernard could know the date is if it were on a day that occurred only once. Since Albert knows the month and knows it's not May or June, he knows Bernard doesn't have enough information to know the entire date, and thus can say with certainty that Bernard doesn't know the date. Thus it has to be in July or August. Bernard picks up on Albert's logic and realizes it can't be in May or June. He says he now knows what the date is. If it were the 14th (which occurs in both July and August), he wouldn't know. So it must be July 16, or August 15 or 17. Since Bernard knows the day he now knows the month too because there's only one option for each day. Picking up on Bernard's last comment, Albert too now knows it can't be the 14th and can only be July 16 or August 15 or 17. And since Albert says he knows the date, it has to be in July. If the month were August, Albert still wouldn't have enough info to know the day because there would still be two options available. But since he does know the date, we know it has to be July. If this isn't enough for you, I don't know how to help you.
Yes he does. For two reasons. First, she told Albert the month. If she told him anything other than May the yes, he knows for a fact she didn't tell Bernard the 19th because the 19th doesn't occur in any other month. Second, if she had told Bernard the 19th, Bernard would know the exact date because only one month has 19. The same goes for June 18. The only way Bernard can know the date at the start is if it's May 19 or June 18. And the only way Albert can say for sure that Bernard doesn't know is if she told him a month other than May or June.
No it isn't. You're actually doing the same line of confusion that Kyakko is. The problem stated "I know Bernard doesn't know your birthday." Spoiler that implies Bernard can figure it out with a number only, but Albert knows he doesn't have one of those two numbers. It says nothing about Bernard being able to eliminate a month, without more info.
This was big in my office like a few days ago. Entertaining to watch older men 50s-60s go at it in the email, while CCing half of the office. They both got to the same correct answer, but with different ways and argued whose method was better. They made colored charts and everything. The best conclusion is:
This question is only confusing because of the Singapore English wording which totally sUcks. The Times ran an article about it that reword ed it to be more sensible.
100% agreed. I work with many Singaporeans and it took some getting used to with their Singlish. Although they speak much better than this question.
Albert knows Bernard does not know the birthdate so that eliminates the months that have a unique date - May and June. Bernard, given this information now knows the birthdate, so that eliminate July and August 14th. That leaves July 15th, and August 15th and 17th. The only way Albert could now know is if he has July, because August has two possibilities left. So the answer is July 15th.
So... Now that they've figured out Cheryl's little secret, should Benard and Albert reward or punish her for being such a mysterious little girl? Edit: this reads a lot creepier then it did in my head. Haha
