200g sol sare cu concentratie 20% se adauga 800 g apa. aflati concentratia finala

Răspuns :

200g=md+mapa=ms
[tex]c = \frac{md}{ms} \times 100[/tex]
md= c×ms/100=20*200/100=40g
msfinal= 200+800=1000
[tex]cfinal = \frac{md}{msfinl} \times 100 \\ cfinal = 40 \div 1000 \times 100 = 4\%[/tex]