A 189 g sample is separated into three materials in the ratio 2:3:4. Enter the mass of the middle share in g.
Bonne réponse
63
Explication
The terms total 9 parts, so each part weighs 21 g and the middle 3-part share weighs 63 g. Dividing 189 by the middle term alone would wrongly assign the whole sample to just three parts.