Cheryl’s Birthday Versi Sang Indra

_82299333_24e94c5d-dc7b-4590-8f46-29d0da74c8b8Yeah The Awesome Question About Cheryl’s Birthday

I wanna solve with my version of logic thinking. It may not pleased some people but it really pleased my logic a lot.

But before I get to that point I wanna try to criticize the majority Answer of July 16

And before I criticize that majority Answer I need to point out some basic rule for that question

1. Albert only know the Month, there’s no way he could know the date before Bernard Say something

2. Bernard only know the Date, but Bernard could know the Month because Albert is speaking first

3. Albert speak first, after that Bernard, after that Albert, the situation is changing in each of the statement being told.

4. Albert know that Bernard is being told the Date by Cheryl

5. Bernard know that Albert is being told the Month by Cheryl

6. The only and true statement is what’s been said by Albert and Bernard.

Ok so let’s take a look the majority answer of July 16

First we need to figure out if Albert knows the month or the day. If he knows the day, then there is no chance that Bernard knows the birthday, so it must be that Albert knows the month.

From the first statement, we know that Albert is sure that Bernard doesn’t know the birthday, so May and June should be ruled out (the day 19 only appears in May and the day 18 only appears in June). In other words, if Albert had May or June, then he cannot be sure that Bernard doesn’t know, since Bernard could have had 18 or 19.

Following that statement, Bernard knows that May and June are ruled out.

Then, Bernard is able to know which month it is. So it must be either July 16, August 15 and August 17 (not 14th as then he can’t know).

Since Albert subsequently can also be sure of the date, he must know it’s July. If it’s August, he can’t be sure as there is August 15 and 17.

So the answer is July 16.

Flawed  statement from above Logic thinking is located on

“From the first statement, we know that Albert is sure that Bernard doesn’t know the birthday, so May and June should be ruled out (the day 19 only appears in May and the day 18 only appears in June). In other words, if Albert had May or June, then he cannot be sure that Bernard doesn’t know, since Bernard could have had 18 or 19.”

Why flawed, because Albert only know the Month, and Bernard haven’t said a word. So how can we sure that Albert know that the date is not 18 or 19? Remember Albert speak first, and he only know the Month, Bernard haven’t said any clue at all. So here. the one and only possible situation for Albert to say that “I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too” is when

ALBERT REALIZE THAT THE MONTH IS NOT JUNE OR JULY

Why?

If the month is June or July, Albert would Assume Bernard know the birthday immediately, since all date in June and July are Unique Number. So Albert can only deducted that he know that Bernard does not know, only when he is being told by Cheryl that the month is May or August. Remember Albert doesn’t know the date, and Bernard haven’t said a Word

Agree? So lets eliminate all date in June + July from the possible date

June 17, June 18, July 14, July 16

The only remaining date is

May 15, May 16, May 19

August 14, August 15, August 17

\

Then lets move on to the second statement

Bernard : “At first I don’t know when Cheryl’s birthday is, but I know now”

Statement above means that Bernard finally know that the possible Month for Albert to be so sure that he didn’t know the date is between May or August, Seeing that month possibility in Bernard who already know the Date can easily predict the Birthday of Cheryl

But the question for us is, how do we predict what’s on Bernard mind?? 😀

Here goes another reduction

Since August 15 and May 15 is redundant, then we need to eliminate that date otherwise the statement of Albert wouldn’t be “At first I don’t know when Cheryl’s birthday is, but I know now”, Albert will still confuse if cheryl told him that the date is 15.

Cheryl wouldn’t tell 19 too, because if she did Bernard didn’t need to say “At first I don’t know when chery’l birthday is”, he would have known the birthdate right away if Cheryl told Bernard that the date is 19 or 18.

So the date

August 15, May 15, and May 19 is off the topic for Bernard’s statement to be trure

So lets eliminate : August 15, May 15, and May 19

Now the elimination date become like this

Albert :”I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too”

Date eliminated :   June 17, June 18, July 14, July 16

Bernard : “At first I don’t know when Cheryl’s birthday is, but I know now”

Date eliminated :   August 15, May 15, and May 19

Possible Date for Now : August 14, May 16 and August 17

Now lets move on the last stement of Albert and the key to unlock this mystery

Albert : “Then I also know when Cheryl’s birthday is”

But before we analyze that statement we need to get back to Bernard statement first, since this two statement is strongly correlated.

Bernard : “At first I don’t know when Cheryl’s birthday is, but I know now”

 When bernard said that “but I know now” that’s indicate that Cheryl possibly told him the number between 14, 16 and 17. And from this point Bernard could easily predict the Birthday because he knew the exact date. The question is for us which one is the real date being told by Cheryl. Same problem for Albert.

But miraculously Albert said that because he know that Bernard knew the birthday right after Bernard knew the Month is between May and August, Its only come down to one and only possibility

Cheryl told Albert that the month is May

Cheryl told Bernard that the date is 16

Why?

Because May 16 is the only possible date for Bernard to be able to say “At first I don’t know when Cheryl’s birthday is, but I know now” and Albert to be able to say Albert : “Then I also know when Cheryl’s birthday is”

Below is the longer explanation. Lets group up the date based on the date since Albert only know the Month

May : May 16

August : August 14 & August 17

If Bernard being told that the date is 14 or 17 than Albert would need to choose 2 possible date in August, that’s mean he can never conclude what is the real date of Cheryl’s birthday

But because Albert right away know the date after Bernard told him that he knew the Birthday. That’s mean Cheryl told Bernard the number of 16. which mean Bernard can just predict that the month is May. Because there’s only one possible date which Bernard could predict the month Right away

THE ONLY MONTH WHICH HAVE ONLY ONE POSSIBLE DATE.

WHICH IS MAY

So yeah, this is my answer

MAY 16 IS THE REAL BIRTHDAY OF CHERYL

Of course Correct Me of My Mistake

Thanks for reading

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