1)
ms=150g
c=15%
md(adăugată)=150g
[tex]c = \frac{md}{ms} \times 100 \\ md = \frac{c \times ms}{100} \\ md = \frac{15 \times 150}{100} = 22.5g[/tex]
md1=md+md(adăugată)=22,5+150=172,5g
ms1=ms+md(adăugată)=150+150=300g
[tex]c1 = \frac{md1}{ms1} \times 100 \\ c1 = \frac{172.5}{300} \times 100 = 57.5\%[/tex]
2)
md1=172,5g
ms1=300g
c1=57,5
m apă(adăugată)=100g
ms2=ms1+m apă(adăugată)
ms2=300+100=400g
[tex]c2 = \frac{md1}{ms2} \times 100 \\ c2 = \frac{172.5}{400} \times 100 = 43.12\%[/tex]
3)
ms1=200g
c1=10%
ms2=800g
c2=5%
[tex]c1 = \frac{md1}{ms1} \times 100 \\ md1 = \frac{c1 \times ms1}{md1} \\ md1 = \frac{10 \times 200}{100} = 20g[/tex]
[tex]c2 = \frac{md2}{ms2} \times 100 \\ md2 = \frac{c2 \times ms2}{100} \\ md2 = \frac{5 \times 800}{100} = 40g[/tex]
md=md1+md2=20+40=60g
ms=ms1+ms2=200+800=1000g
[tex]c = \frac{md}{ms} \times 100 \\ c = \frac{60}{1000} \times 100 = 6\%[/tex]
