 Na imagem visualizamos o logotipo do projeto 'MatematiZou', escrito com letras de forma na cor verde-azulada. A letra “Z” está na cor branca dentro de um hexágono com pontas arredondadas preenchido na mesma tonalidade de cor do restante das letras.  Na imagem temos um mini caminhão branco de madeira, cuja caçamba é azul escura e está escrito em letras brancas “UFABC”. As rodas do caminhão são vermelhas e quadradas. Cada par de rodas do caminhão está em cima de uma pista com ondulações.  Na imagem, há várias pessoas participando do evento “UFABC para todos” no Ginásio da UFABC campus Santo André. Algumas pessoas estão ao redor de uma mesa com jogos que incluem copos, mapas, tabuleiro de xadrez, entre outros, e outras, estão vendo as exposições espalhadas por todo o ambiente.](https://matematizou.gradmat.ufabc.edu.br/files/LogoMatematizouTeal.png)
History
Although there may not be a specific reference about the exact origin and usage of this problem it is known that the two-plated scale originates in Ancient Egypt and it is still used today. It is possible that the problem had been proposed in an educational context or as a challenge in antiquity, but there was no historical evidence to support this.
Nowadays, the challenge of the weight of the coins is used as an educational activity for children and also in mathematical and logic competitions all over the world. It is a fun and challenge way to develop skills related to logical reasoning, mathematic, problem solution and it is used in many kinds of job interview and programming tournaments.
There are many versions of the problem, some including coins with weight differences in many levels of difficulty. Each solution presents its own challenges and limitations. The option for the best solution depends on the context of the problem and the available resources. disponíveis.
Description:
The challenge “finding the heaviest coin” is a classical logical puzzle problem where you have a quantity of coins apparently identical but one of them is heavier than the others. The objective is to find out which one is the heaviest using just a two-plated scale. Try using the least amount of weight-ins.
Instructions:
1. Put the balls where you wish to weight in the orange boxes, each box represents one side of the two-plated scale.
2. By clicking at “Pesar”, the scale will identify witch side is heavier.
3. Put the balls that you consider not being the heaviest in the in the “area of disposal”.
4. Put the ball you think is the heaviest in the “test area”.
Learn more
There are many variations to this problem, as having to find the lightest coin instead of the heaviest, or having many fake coins. But the main point is the same: finding the different coin in the pile using just a two-plated scale and a limited number of weigh-ins. Some references are:
http://clubes.obmep.org.br/blog/problemao-duas-moedas-falsas/
http://clubes.obmep.org.br/blog/probleminha-moedas-falsas/
https://www.obm.org.br/content/uploads/2017/01/balanca-leve.pdf
It is worth to mention that these sites are written in Portuguese (Brazil).
