Teaser Tuesday! January 21, 2014

Got a couple of fun ones you might see during an interview! Enjoy!

Note: If you could all please input your answers using the previously noted html code it will allow others to answer without having a spoiler. Also, in your answer, do not include any ' or " or it will not work properly.

Question 1

There is exactly one week between Christmas and New Year. Thus a New Year that occurs right after the Christmas, happens to occur on the same day as Christmas. But in 2030, Christmas will occur on Wednesday and New Year will occur on Tuesday.

How is that possible?

Question 2

Two friends were stuck in a cottage. They had nothing to do and thus they started playing cards. Suddenly the power went off and Friend 1 inverted the position of 15 cards in the normal deck of 52 cards and shuffled it. Now he asked Friend 2 to divide the cards into two piles (need not be equal) with equal number of cards facing up. The room was quite dark and Friend 2 could not see the cards. He thinks for a while and then divides the cards in two piles.

On checking, the count of cards facing up is same in both the piles. How could Friend 2 have done it?

Good luck!

6 Comments
 
Best Response
1 is easy... 2 is more mathematical but still not too bad...
Frank Sinatra - "Alcohol may be man's worst enemy, but the bible says love your enemy."
 

It asks "how is it possible". So for it to be possible, the other friend would have to flip 15. That's the point of the riddle.

Frank Sinatra - "Alcohol may be man's worst enemy, but the bible says love your enemy."
 

Um...since it's an odd number of cards (15) it can never be equal. At best you would have 8 in one pile and 7 in the other. Unless I am not understanding this correctly.

 

Friend 1 flips 15 random cards.

Friend 2 takes X number of cards off the top. Say, in that pile, there are n cards flipped, so in the other pile there are 15-n cards flipped. There is no way to be sure that n = 15-n, 1. because 15 is odd, and 2. because we have no idea where these cards are. So lets say we invert the entire pile of X cards. Now there are X-n flipped cards in our pile and still 15-n flipped cards in the other pile. For these to be equal, we need to take X=15 cards off the top.

 

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