Skip to main content

Guess the Number


Sage had a 1, Rosemary had an 11, and Tim had a 2.

From Sage's statement, he had to have an odd number. He knew that the sum of all three numbers was even, so if his number was odd, one of the other two numbers would have to be odd, and the other even, leaving them unequal.

Rosemary could deduce this, too, so when she saw an 11, she knew that Sage had a 1 and Tim had a 2. If she had seen a 12, she would have known that the other two boys each had a 1, which is contradicted by her saying that she already knew they all had different numbers. If she saw any number other than an 11 (say 9, for example), she would not have know which odd number Sage held. (In our example, he could have had a 1 and Tim a 4, or he could have had a 3 and Tim a 2).

Tim, understanding all of this, therefore knew their numbers.

Comments

Popular posts from this blog

Chris's Birthday

  If today is January 1st, and December 31st was Chris' birthday and she turned 8, and on December 30 Chris was 7, and this year Chris will turn 9, then next year Chris is turning 10.

What are we?

    The number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 0 on a US keyboard when you hold the shift button down.

Murder!!!

   Ans : 16 Name the 10 people with letters: A, B, C, ... and so on. A through F each call any one of G, H, I, or J (it doesn't matter which one). That makes six calls so far. Then G calls H and I calls J, after which G calls I and H calls J. Now we've used 10 calls, and G, H, I, and J all know everything. Finally, each of A through F is called by someone in G through J - 6 more calls to get everyone knowing everything. 16 calls in all.