Răspuns:
a) 14%
Explicație:
ms₁ = 400g
c₁ = 20%
ms₂ = 600g
c₂ = 10%
c₃ = ?
md₁ = c₁ms₁ / 100 = 20 × 400g / 100 = 80g
md₂ = c₂ms₂ / 100 = 10 × 600g / 100 = 60g
md₃ = md₁ + md₂ = 80g + 60g = 140g
ms₃ = ms₁ + ms₂ = 400g + 600g = 1000g
c₃ = md₃ × 100 / ms₃ = 140g × 100 / 1000g = 14% → varianta a)
-Mihai