A Missing Key

Logic Level 1

Clarification : Only one of these 3 boxes has the key.

Box 1 Box 2 Box 3 Not enough information

2 solutions

Angela Fajardo
Mar 23, 2016

Since all of the statements are false :

From the 2nd statement: The key is not in Box 3.

Assuming that is it false, we "reverse" the statement: The key is in Box 3.

Therefore, the answer is Box 3

In order to double check, here are the "reversed" statements from the other boxes:

Box 1 : The key is not in Box 2

Box 3 : The key is not in Box 1

Edit: The reverse in the statement is called a negation ( @Sravanth Chebrolu )

Nice solution!

If you can, mention that the reverse in the statement is called a negation . $\ddot\smile$

Sravanth C. - 5 years, 2 months ago

Thanks, didn't know what its called.

Angela Fajardo - 5 years, 2 months ago

Www Www
May 6, 2016

We can easily know that the key is in Box 3, because since Box 2 states that the key isn't in Box 3, and we know all the statements are false, the key must be in Box 3. But just to make sure, it is stated that the key is in Box 1, and since the statements are false, the key cannot be in Box 1. Same with the statement that states that the key is in Box 2. So this leaves us with Box 3.

A Missing Key

2 solutions

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