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Cate grame de zahar trebuie sa se adauge peste 200 grame de solutie de concentratie 10% pentru a se obtine o solutie de concentratie 40%?

Răspuns :

ms = 200g
C = 10%
Cf = 40%

C = md/ms*100 => md = C*ms/100 = 10*200/100 = 20g zahar

Cf = md+x/ms+x*100 <=> 40 = 20+x/200+x*100 <=> 40(200+x) = 2000+100x <=> 8000+40x = 2000+100x <=> 60x = 6000 => x = 100g

md adaugat = 100-20 = 80g zahar