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Formal Reasoning (Posted on 2004-12-15) Difficulty: 2 of 5
I present to you a deck of 4 cards. Each card has on one side a letter of the alphabet, and on the other side a single digit from 0-9.

I propose a hypothesis that may apply to this deck:
If the letter is 'E', then the number on the other side is '4'.

I then drop the 4 cards on the table, and you see: 'B', '7', 'E', '4' (on the respective cards).

Which of the 4 cards must you turn over to verify or disprove my hypothesis?

See The Solution Submitted by SilverKnight    
Rating: 3.0000 (22 votes)

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Solution Layman's Logic | Comment 9 of 60 |
"If the letter is 'E' then the numbre on the other side is '4'"

You certainly need to turn over the 'E' as the hypothesis mentions no other conditions, if the reverse is not a '4' then the hypothesis is false.

it does not mean that the otherside of a '4' is always an 'E'

You also need to turn over the '7', if it's an 'E' then the hypothesis is again false.

  Posted by Juggler on 2004-12-15 15:50:28
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