The riddle of the Two coins of 3 € It is as simple as insidious:
If I have two coins in hand that added 3 €, but one cannot be from € 1, what coins I have in hand?
On two feet, It seems … Impossible! There are no € 1.5 coins. Yet, the solution There is and is also extremely simple. We see it in this article.
The solution of the trigger of the two coins of 3 €
If you have not been able to find the solution, don’t worry, you are in good company. This riddle, In fact, it is formulated precisely in such a way in trick our mind and make the request appear as impossible. This is because when we read “(…) One cannot be 1 € (…)” We are led to think that it means
None of the coins can be from € 1.
With this interpretation the riddle does not actually have a solution! If we exclude the use of the € 1 coin, we cannot find two coins in the system of euros which, added, give as a result of € 3.
So what is the solution? Let’s go back to the text of the indovinel, the makeup lies in asking:
If a it cannot be from € 1, then the other coin How much can it apply?
The riddle gives us one stringent condition on only one of the two coins! We are not told anything about the other coin which, therefore, can safely be from € 1.
So the solution will be as simple as possible:
The first coin, the one that cannot be from € 1, will be from € 2. While the second coin, which has no condition, will be from € 1.
SUMMA, they do just € 3!
Why does the deception of the two coins work work?
Riddles like this play on difference of meaning that certain words can have in the field mathematical compared to common spoken language.
Let’s take the sentence for example:
A person must eat and drink if he wants to survive
With this sentence we mean that all people need to eat and drink to survive. But in Matematica, to say the same thing, we should write:
Everything is fine person must eat and drink if he wants to survive
Words like “Everything is fine” And “a”in mathematics, are called quantifiers And they indicate precise quantities, without under the underworld. This means that “Everything is fine” it means “all”, While “a” it means “Exactly one”.
Returning to the case of the IndoVinello “a” it does not mean both as the riddle has led us to think, but it means that specifically only one of the two coins cannot have that value, but the other yes!
