Maths|Logic - (1 Viewer)

[AnthonyGerrard]

http://i.guim.co.uk/static/w-700/h-...992c-012d-4216-9e7a-2751a79c75c4-620x372.jpeg

A problem from Singapore - its easily cheatable on the tinterweb should you wish!

 

[spikepl]

Cheryl is a stupid bitch

 

[AnthonyGerrard]

cheryl is a stupid bitch :d

True enough! It may be better just to wait till she goes nuts for not receiveing a birthday present!

 

[spikepl]

In any case: logically I can get to May 19 or June 18, but not able to narrow it down further.

 

[AnthonyGerrard]

In any case: logically I can get to May 19 or June 18, but not able to narrow it down further.

It cant be either of those as Bernard would know initially what the bday was just from the number.

 

[spikepl]

Isn't that what the text says? After the sneaky bitch told him the date he could tell - the moment he could do that, then Albert, knowing the right month, also knew which of the two possibilities it was.

 

[AnthonyGerrard]

Isn't that what the text says? After the sneaky bitch told him the date he could tell - the moment he could do that, then Albert, knowing the right month, also knew which of the two possibilities it was.

No - only after Albert spoke did Bernard know the bday and month.

 

[Brianwarnock]

June 17 ?

Brian

 

[Brianwarnock]

How the hell fdo you find the answer on the web?

Brian

 

[vbaInet]

One of August 15, June 18 or May 19?

 

[vbaInet]

Just noticed that spikepl had already mentioned my last two so I'll stick to August 15?

 

[AnthonyGerrard]

Noones got it so far.

 

[spikepl]

I think Bernard is a nasty boy - he cheated!

 

[AnthonyGerrard]

I think Bernard is a nasty boy - he cheated!

Shall I share the answer yet ? May put it in faint, so it not a giveaway for anyone unless they want the answer.

like this!

 

[Brianwarnock]

Correction august 17

Brian

 

[AnthonyGerrard]

Correction august 17

Brian

Its not the answer I have !? Maybe you could show you workings.

 

[BlueIshDan]

I'm thinking June 18

 

[Brianwarnock]

Its not the answer I have !? Maybe you could show you workings.

A knows the month and B knows the day
Since B doesn't know we can obviously rule out the single days May 19 and June 18
But since A knows that B doesn't know he can also rule those out, which since he still doesn't know that also rules out June 17, which is where I answered too quickly first time.
Onto second sentence
With A still not knowing and thus ruling out June 17 the only possible solution is August 17 as it is the only unambiguous day.

That's my 2p worth. Hoped I explained my logic ok.

Brian

 

[BlueIshDan]

I agree with August 17th actually

 

[Frothingslosh]

Oh, for the love of God.

I had no intention of contributing here ever again, but this is driving me insane, watching you people flounder about.

The birthday is July 16.

• A knows for a fact that B cannot know the exact birthday. As he knows the month but not the day, that means the month is one without a unique day listed. This eliminates both May (the 19th) and June (the 18th).
• B realizes the above. Since he knows the day and now is aware that it must be either July or August, this tells him the exact birthday. This means that the day CANNOT be the 14th, or he would not have figured that out.
• A now knows the above. Since he knows the month, and now knows that it cannot be the 14th, he also knows the exact date. If the month were August, he would not have been able to determine the exact day, so this eliminates August, which had both the 15th and the 17th remaining.
• The only date meeting the above criteria (Not in May, June, or August and not the 14th) is July 16, making that the birthday.