105. Out of 52 Cards 13 Are up and 39 Are Down and Are Mixed
Out of 52 cards 13 are up and 39 are down and are mixed .
How to arrange them in two decks of equal numbers of up.
Condition
You are sitting in a dark room and there is no light.
Submitted by tartle · Added 11 April 2010
Solution:
Separate the cards into two piles: one with 13 cards and the other with 39 cards. Flip all the cards in the pile of 13. This way, if the pile of 39 has x face-up cards, the pile of 13 will have 13-x face-up cards, and flipping it will result in both piles having x face-up cards.
Comments (5)
can you give a small hint ?
Saperate the piles into 2 equal piles of 26 cards each. Flip all the card of on pile. I think this question is simmilar to the 20 coin question.
The correct solution is like this:
Saperate the piles into 2 piles of 13 & 39 cards each. Flip all the card of smaller pile.
divide in two pile one with 13 and other with 39.
flip the cards of pile 13.
explanation: say pile with 39 has x up cards so card with pile 13 has 13-x up cards means it has x down cards so if u flip u will have x up cards same as pile with 39 cards
So far everyone has a correct solution that yields the same number UP in each pile.
However, Lonewolf's solution accomplishes this AND the same number DOWN in each pile.
Simply split into 2 equal piles and turn one upside down.
Add a Comment or Suggest an Answer