Thirty pounds of a salt-water solution contains fifteen percent salt. How much water must be added to weaken the solution to ten percent salt?



Answer :

luana
[tex]Formula\ for\ percen\ concentration:\\ Cp=\frac{ms}{mr}*100\%\\\\ ms-mass \ of\ substance\\ mr- mass\ of \ solution\\\\ mr=30 pound\\ ms=x\\ 30 \ pounds\ of \ salt-water\ solution-----cp=15\%\\ 30 \ pounds\ of \ salt-water\ solution + x\ water --cp=10\%\\ 15\%=\frac{ms}{30}*100\% \\ \frac{15}{100}=\frac{ms}{30}\\ 100ms=15*30\ |:100\\ ms=4,5\ pound\\ 10\%=\frac{ms}{30+x}*100\%\\ \frac{10}{100}=\frac{4,5}{30+x}\\ 10(30+x)4,5*100\\ 300+10x=450\\ 10x=150\ |:10\\ x=15 pound\\ [/tex][tex]15\ pounds\ of\ water\ must\ be\ added.[/tex]

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