X Implies Y

By | April 1, 2010

Part I

(you can’t use paper, you have to figure it out in your head)

i have a black triangle, a white triangle, a black circle and a white circle.  if i gave you a shape (triangle or circle) and a color (black or white), the “frobby” items would be those that had either the shape or the color, but not both.  that is, in order to be frobby, the item must be of the specified color OR the specified shape, but not both the specified shape AND the specified color.  i’m thinking of a shape and a color in my head and i tell you that the white triangle is frobby.  can you tell me the “frobbiness” of the other items?

Part II

there are four cards which have a letter on one side and a number on the other side.  i lay them out and the cards appear as 2 5 F E.  the rule is that a card with an odd number on one side must have a vowel on the other.  what is the minimum number of cards you should turn over to prove the rule is true (and which cards would they be)?


You may be able to find the solution on the discussion forum.