Spin off of another thread, test how smart...

[Yax]

Okay, so I read the thread about the prof and two students with cards,etc:
Link

I showed it to my little bro, he said he saw that question on a school exam (extra credit question). That got me to thinking. It was published already so if someone was able to answer it, that doesn't necessarily mean they were smart. They could have just seen the answer before. So on my way to work today, I thought of another question along the same line (this one seems easy, but lets see how everyone does. (Note, if you looked at the other problem first, it will probably better prepare you to answer this one).

Problem:
So, say Professor Jhon had the cards below:

Hearts: A, Q, 4
Spades: J, 8, 4, 2, 7, 3
Clubs: K, Q, 5, 4, 6
Diamonds: A, 5

This time he tells Jack the card number and Tom the suit of one of the cards. Now they have to figure out which one it is.

conversation:
Jack: I don't know.
Tom: oh, now I know.
Jack: ahh, I know it now too.

So, which card is it now?

 

[Haircut]

4 of Spades

BTW Shouldn't it be Tom who says that he knows, in the second line of speech

 

[z0mb13]

please explain .....

 

[Yax]

Originally posted by: Haircut
4 of Spades

BTW Shouldn't it be Tom who says that he knows, in the second line of speech

Thanks, I edited it to say Tom.

Must have been too easy. 4 of spades is correct.

------------------
Problem:
So, say Professor Jhon had the cards below:

Hearts: A, Q, 4
Spades: J, 8, 4, 2, 7, 3
Clubs: K, Q, 5, 4, 6
Diamonds: A, 5

This time he tells Jack the card number and Tom the suit of one of the cards. Now they have to figure out which one it is.

conversation:
Jack: I don't know.
Tom: oh, now I know.
Jack: ahh, I know it now too.
-----------------

When Jack said I don't know, the only way Tom could have figured it out would be because he was told Spades. Knowing that it was spades and that Jack didn't know, the answer, Tom would know that Jack was told 4. If Jack was told any other number like J, 8, 2, 7, or 3 he would already know which card it was since those numbers are unique to spades so he would not say he didn't know.

If Tom was told any other suit besides Spades, there's no way he could have figured out which card it was when Jack said: I don't know. This was because all other suits contain more than one non unique cards. So that eliminates all the other suits from our list of choices.