Question

Se amesteca 15 g de sirop de zmeura de concentratie 10%,cu 200 g de concentratie 30% .Care este concentratie procentuala a solutie rezultate prin amestecul celor doua?

Answer 1

c/100 = md / ms 

in prima solutie, c1 = 10%, ms1 = 15 g , md1 = c1 x ms1 / 100 = 10 x 15 / 100 = 1,5 grame 

a doua solutie, c2 = 30%, ms2 = 200g  md2 = c2 x ms2 / 100 = 30 x 200/100 = 60 g

in solutia finala avem
  ms = ms1 +ms2 = 200 g+ 15 g = 215 g 
  md = md1 + md2 = 1,5 g + 60 g = 61,5 g 

c = md x 100 / ms = 61,5 x 100 / 215 = 28, 60% 

Answer 2

c = md*100/ms
md1 = ms1*c1/100 = 15*10/100 = 1,5 g
md2 = ms2*c2/100 = 200*30/100 = 60 g
md3 = md1+md2 = 60+1,5 = 61,5 g
ms3 = ms1+ms2 = 15+200 = 215 g sirop
c3 = md3*100/ms3 = 61,5*100/215 = 28,6 %