Question

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

Answer 1

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