ms=masa solutiei=200g
ci=concentratia initiala=10%
cf=concentratia finala
mdi=masa dizolvantului(zahar) initiala
mdf=masa dizolvantului(zahar) finala
rezolvare:
ci=(md*100)/ms => mdi=(ci*ms)/100=10*200/100=20g
mdf=mdi+ 30g => mdf=20+30=50g
cf=(mdf*100)/ms =>
cf=(50*100)/200=25%