Try to answer this on your own
suppose I give you four cards labeled with the letters A and D and the numbers 3 and 6. The rule of the game is that a card with a vowel on it always has an even number on the other side. Which cards you have to turn over to prove this rule is true ???
The answer is two cards the A and 3
most of the people will reply A or A and 6
How to prove this is right, here is the question in other way
four people are in a bar, one is drinking coke, the other is sixteen, the other is drinking beer and the fourth is twenty five.
Which IDs do you have to check to make sure no one below 21 is drinking.
the answer is clear the 16 and the beer drinker and most of the people will get that right.
When it comes to people the human mind is perfect, but at some facts it abstracts it stops at concentrating on other stuff. I like this quiz very much from the book the for .