A simple technique to distinguish between red and blue marbles of the same size and mass is to use a color detection method, such as a camera with image processing software or a color sensor. This allows for the automatic identification of the marbles based on their color. Alternatively, a manual sorting method can involve using a light source to visually separate the marbles by color.
Chromatography
That would depend on how many yellow and blue marbles are in a pack. If yellow and blue marbles are sold separately and there are the same number of marbles in a pack, buy one of each. That's probably not the case.
In order for 4 red marbles to be one-third of a group and 3 blue marbles to make up one-fourth of the same group the number has to equal 12.
7.5 grams
7
A technique called chromatography or a technique called filtration could be used to separate the red and blue marbles. chromatography would depend on the differences in solubility between the red and blue marbles, while filtration would depend on differences in size or density between the marbles.
Chromatography
6
That would depend on how many yellow and blue marbles are in a pack. If yellow and blue marbles are sold separately and there are the same number of marbles in a pack, buy one of each. That's probably not the case.
In order for 4 red marbles to be one-third of a group and 3 blue marbles to make up one-fourth of the same group the number has to equal 12.
7.5 grams
There has to be 12 marbles in the group. If 4 are red that is 1/3 of 12 and if 3 are blue that is 1/4 of 12. The rest can be any color. That is how you explain how four red marbles can make up 1/3 of a group of marbles and three blue marbles make up 1/4 of the same group :)
7
minus one red marble plus one blue marble
1 in 5.45 of picking at least 2 blue marbles any 2 from 3 is 3 correct picks =3X7(red)=21 of 2 blue only 1 pick of 3 blue only any 3 from 10=120 120/22=5.45
The density of one marble is the same as the density of six marbles when compared in terms of mass per unit volume. Since the density remains constant regardless of the number of marbles, the ratio of their densities is 1:6.
Density is mass per unit volume. More marbles is more mass, but will be more volume as well. If the marbles are all the same, any number of them will have the same density, which is 2.5 grams/cm3. This is a "thinking" problem rather than a "calculation" problem.