There is a box with 20 red balls, 10 green balls and 5 black balls. How many balls do we have to extract at least to get four balls with the same colour?
CLUE: Think about the worst possible situation.
Use comments to answer, writing your name.
(Translated from: 100 problemas de ingenio by Capó, M.)
Javier Anglada. 1º ESO B The answer is ten balls. The smaller number of balls you can extract without having four with the same colour is nine (3+3+3). If you extract another ball, regardless of colour, you will have four equal balls.
I change my answer you have to take 12 because the worse situation is that you do not take any balls at the same color so is 4 times 3. Ana Sevilla Moreno 1ºESO B
I think that it's 10 balls.
ReplyDeleteI'm not sure, but I think we have to extract 10 balls.
ReplyDeleteWe have to extract 29 balls
ReplyDeleteMarina Varas Santolalla 1ºESO B
ReplyDeletePara sacar 4 bolas del mismo color hay que sacar al menos 17 bolas
We have to extract 6 balls.
ReplyDeleteJulia Rodríguez Pedrera 1ºESO B
SOLUCION:10 BALLS
ReplyDeleteComo mínimo, son 4 las que se necesitan, aunque hay una probabilidad pequeña de que salgan las 4 primeras del mismo color.
ReplyDeleteJesús Mejías Cabello de Alba 1ºB
If you take 4 balls you have posibilities to get all with the same color, so, 4 is the minimun
ReplyDeleteAna Sevilla Moreno 1ºESO B
la peor opcion es sacar diez bolas y tendriamos cuatro bolas de un mismo color necesariamente
ReplyDeleteIs to take 10 balls at a minimum.
ReplyDeleteCarlos Gracia Mármol 1 ESO B
10
ReplyDeleteJavier Anglada. 1º ESO B
ReplyDeleteThe answer is ten balls.
The smaller number of balls you can extract without having four with the same colour is nine (3+3+3). If you extract another ball, regardless of colour, you will have four equal balls.
mari angeles ruz
ReplyDeleteprofesor me ha costado mucho trabajo y no se si esta bien...
SOLUCION: hacen falta sacar 28 bolas
Hay que extraer 17 bolas para conseguir 4 del mismo color.
ReplyDeleteNoelia González Oteros 1ºB
Marina Varas Santolalla
ReplyDeleteCambio mi respuesta enviada a: Hay que sacar como minimo 10 bolas.
I change my answer you have to take 12 because the worse situation is that you do not take any balls at the same color so is 4 times 3.
ReplyDeleteAna Sevilla Moreno 1ºESO B
The right answer is 10 balls, if you want to know why, read Javier's comment.
ReplyDeleteCongratulations!!